Interior leaking

Now, before I begin I’m no expert but this is the type of guide I would have liked to walk me though tracking down this leak. This is a step by step guide. I have done my research. The forum at helped me track down what the problem was.

Picture the scene, I’ve spent five hours cleaning the car, a nice shiny polished beast. A quick final hoover of the inside and disaster… water in the back of the car. It was just a small puddle but still it was there…. in my car…. uninvited…. bastard bloody water.

So I did some research. I discovered that the transmission control and comfort control modules are under this section of floor. You don’t have to know what these are, all you need to know is that they are expensive to put right if they go wrong and sitting in water is just the kind of thing that might make them do that.

I did some more research and found out this could be caused by a blocked drain hole under the pollen filter. I looked for a good hour and couldn’t find a guide so made one myself and this is it. Like I said, I’m no expert but I have written the type of guide I would have liked to have had to hold my hand while I tried to sort the leak.

If there are some funky things happening with your electronics you probably have something wrong with your Comfort Control Module (CCM), or at the very least, the wiring harness. Have a look at the VW Passat Comfort Control Module harness repair page on HeadFuzz.

Are you sitting comfortably?

Yes? Then I shall begin.

Before you begin please read through the guide from start to finish, will save you time if you have a better idea of what your doing. I also recommend you get a Haynes manual if there is one for your car.

If your not very sure of what your doing I recommend you get your digital camera out and take photographs before and during work. That way you can refer back to them if your stuck putting things back together.

OK, here goes. You need to gather some things together -

Socket set, 14mm socket
Size 10mm spanner
some old rags
Big fingers

Step 1 – Having a quick look see

When you open up the bonnet you will see something pretty similar to this. My Passat is a UK 2001 B5.5 so if yours isn’t there are bound to be some slight differences but I can’t imagine anything would be greatly different in a B5 series Passat.

Step 2 – Removing the seal

The first thing you need to do is remove the seal that runs around the edge of the engine to remove the battery cover. The rubber seal just pulls off and the cover just slides out by pulling it towards the front of the car. You should be left with something similar to the image below.

The B5 (2000 and older) does not have a cover over the battery. So don’t panic. It’s not missing.

Step 3 – What is causing the leak ?

This is a close up of the pollen filter which incidentally needs changed, but that’s a job for another day. As you can see there is a line of sludge along the route the water run off should be taking. Over time its this sludge that blocks the drain holes. If your car dosen’t have this sludge the drain holes could still be blocked. Might be worth looking into it anyway.

Step 4 – Getting at the drain holes, Removing the battery

There are two drain holes and to get to them we need to remove the battery and the shelf it sits on, don’t be frightened, its easy really. First off the battery needs to be removed using your trusty 10mm spanner mentioned earlier.

Remove the negative cable (black) terminal first.

Once you have removed both the cables from the battery you will be faced with this which clamps the battery in place.

Using a 14mm socket remove the bolt and clamp which just lifts off.

Wouldn’t life be nice and simple if the battery just lifted out at this point. Well life isn’t and it doesn’t :) , there are a few more steps to go.  This little hose at the right hand side is a run off from the battery and just pulls out.

Step 5 – Removing the cable

The cable marked here needs to be unclipped from the body of the car to allow you to remove the battery.

If you know what this cable is called, can you let me know :)

There are metal clips that slide off if you pull them towards the front of the car.




Step 6 – Lifting the battery out

The shelf the battery sits on has a lip at the right hand side which, together with the clamp we removed earlier hold the battery in place. The battery needs to be slid to the left so it clears this lip then it simply lifts out. Remember though its bloody heavy and contains acid and other nasty stuff. Modern batteries are sealed but its best to keep it level and treat it with a little respect just in case.

The removed battery and clamp. Now its time to take out the shelf the battery was sitting. Here is the battery sitting on my drive, by this point I’m quite proud of myself… and thats the hardest bit done.

Step 7 – Remove the battery tray

Now the shelf the battery was sitting on needs to be removed. It is held in place with two nuts and a bolt. This image shows the top left of the shelf with the nut removed. This one nut holds the alarm sounder (that’s what it looks like to me anyway) in place as well as securing the shelf to the body. The alarm sounder and the shelf slot together so they have to be unslotted. With all the fixings removed and the alarm sounder out of the way the shelf just lifts out.

Ta da, the shelf is out. You can unclip and remove the alarm sounder if you want, I just didn’t want to risk getting the electrical contacts dirty with all the dirt and sludge that was down there.

The battery shelf and fixings sitting in the drive.

Step 8 – Unblocking the drain holes

So that’s the hard bit done, your car should now look something like this. The two drain holes are circled. They are about 2″ across and have a rubber edging. Its easier to see if you look at the drain hole closest to you in the picture. If you poke your finger in you will feel a little rubber skirt. Basically its this little rubber skirt that causes the drain holes to become blocked and in turn flood the interior of the car.

I have read about people removing these rubber skirts. There is logic behind this, if there is no skirt then there not possibility of it becoming blocked. I consulted a friend of mine (you know who you are you big ginger professor of thermo dynamics you) and found out that these skirts are there to stop road spray and other things coming up through the holes. As you can see I left mine in place but the choice is yours.

The big black thing you can see at the top left is the break master cylinder and under this you can see the second drain hole which is very gunked up with sludge.

All clean and unblocked. To clear the blockage all you need to do is give it a quick poke and a wipe with a cloth and the gunk is all gone. When you poke the blockage through it just ends up on your driveway. I pushed a little too hard and the rubber surrounding and skirt went through the hole. Its a pain to get it back up through the hole and reattach so be nice and gentle, treat your car as you would a lovely lady :)

Step 9 – Sticking it all back together

So with everything de-gunked its time to put everything back together. When reconnecting the battery shelf, remember to slot the alarm sounder on the bolt after the shelf is in place or it wont slot together properly.

Slide the battery in place so that its hard up against the lip at the right hand side of the shelf.

Reattach the clamp at the left hand side.

Before you replace the clip on cable shown here you need to make sure the cables you are going to attach to the battery are tucked in this space as shown here. They wont slot through with the larger cable clipped in place.

When clipping the cable in place its exactly the same as removing it.

The battery needs to be reconnected using the good old 10mm spanner.

Re attach the battery run off hose at the right a hand side and check that the other end is pointing towards the newly unblocked drain hole.

Now you can replace the battery cover, the large bit of plastic that covers the area you have been working on.

Step 10 – Replace the seal

Nearly done, the final job to do in the engine compartment is to replace the seal around the engine and battery cover. Start at a corner and make sure that the rubber is pushed in tight. Also check that the battery cover is slotted correctly into the seal. Work your way round pushing it on firmly. Mine squeaked like a fat man on leather sofa, so if you hear that your doing it right.

Replacing the seal starting in the top left corner.

The seal that runs around the engine slots together at two points the left and right, make sure that these are properly slotted together.

Seal in place and joined together.


Now your car should be back together in one piece and you should feel quite proud of yourself and pat yourself on the back for a job well done.

Step 11 – Drying out

I lifted the carpet and scooped out the the majority of the water. Now all that remains is to whip out the hair dryer and get rid of the wet spot.

Step 12 – Victory dance

The offending dirt will be sitting on the driveway, its amazing that this little lump of muck no bigger than a 10p could end up costing so much in repairs. I recommend you kick it about a bit, I ran over it with the car a few times…. it made me feel a little better.

So that’s it, if you use this guide or have any questions or comments please contact me and let me know.

If your looking for technical advice you might be best to try the Passat world forums. I can help with some things but there are people there who really know their stuff.

70 thoughts on “Interior leaking

  1. Brilliant article. Thanks. I just bought a Passat on Ebay, with no front windows working and door locking in a state of disarray. I looked under the passenger side carpet, as per, and, yup, very wet, and the wiring was in a sorry state. So I’ve just finished following your guide above and will now set about drying out the wiring. Brilliant. Thanks.
    What I found was that the drain holes you cleared were actually free of gunk on my car. The problem for me was a build up of wet gunk to the immediate right of the pollen filter. This was the obvious culprit. After I cleared it all out I poured some water down the front screen to check for easy flow. The problem is that there’s only about 6mm of channel to carry the lot …a real bottle-neck. No wonder. I’ll be checking this area for blockage regularly from now on and would recommend that all Passat owners do the same. Looking forward to accessing a car park without having to get out of the vehicle!

    • Agreed this is a great article. Our battery went flat and i opened the battery space to find it sitting in a large pool of water!!! I sucked it out with an aquavac, then i thought – there must be drainholes? then i found this article – thanks. Interior has been wet too – might be the cause.

      One point – the one drainhole can be reached and unblocked with a pices of wire without taking the battery plate out. Good for a quicker process if needed.


  2. I had serious flooding in both front and rear footwell on driver side not obvious as the top carpet was quite dry. Symptoms showed as faulty ABS warning light amongst other random warnings. This was also caused by blockage of drain channels on right of pollen filter housing, under the bonnet hinges. I cleared this (and also drilled a small drain hole in the left corner (lowest) of the filter housing. Dried out the carpet underlay (about a gallon of water) and now all seems to be fine

  3. Pingback: My Very Own Water Intrusion Problem - '01 Passat - ((With Pics!)) - VW Passat Forums : Volkswagen Passat Forum

  4. Fantastic help, thank you. I knew what the problem was, blocked drain holes under the battery, but I didn’t know how to get the battery out. Using your instructions job now done and drain holes cleared. :) :) Just need to dry out back carpet now.

  5. Thanks for all the advice, very useful. I have been to the great VW passat water show and I realised that living in the country doesn’t help as come autumn the leaves fall and block the drain holes. So to combat this problem I installed a piece of 4mm Diameter plastic cable with a small piece of chain attached to the end down the drain hole, so I could weekly pull and push the cable up and down to unblock the hole. I attached the cable to the plastic cover grill accross the engine by the battery, base of the windscreen, so it was handy to lift bonnet and just give it a waggle whilst checking water and oil ,etc. The small chian on the end of the cable is there to guide the cable in to the drain hole as it is not very accessable, so you push the cable with the chain on the end towards the drian hole and when it falls down the hole the cable goes with it! You know when the cable is long enough when it comes out underneath the car and on the ground.

  6. I now possess a low mileage but ageing passat (1999) RHD, diesel.
    Shortly after buying it I was caught in a thunder storm which flooded the left side front and back floor.
    I had to wait for roadside help (near Paris) to come and assist as the water ingress had drenched the electrics under left side dashboard.
    Nice man, dried everytging, looked everywhere and suggested I spend time clearing rain run off drains, which I did; rear from sunroof – clear, front sunroof (inside door openings- blocked so I cut off 1/2 inch rubber “nipple”, then the battery box area – some blockage but was allowing water through).
    As we had a wonderful summer, didnt we? which was rain interpersed with flashes of sun, my car got wetter by the day, and so did the passenger ‘pool’.
    I read all the pages I could find on the matter only to find my pollen filter dry, and only damp water marks around it, but not enough to suggest it had been letting anything past it unlike a certain Manchester United goal keeper recently.
    I braved having a hose slowly pour water over the car while I stayed inside to ‘feel’ and yes I discover it coming from a heater/vent hose left of centre under the dash.
    But where does that hose originate ? I do not see any hose coming through the bulkhead, so would invite vw passat enthusiasts ( or grumbled victims) to enlighten me on where they found the ‘top’ of such a hose.
    I fear if this happened and I was in a -15° frost like last January then I could kiss the vw goodbye.

    Yours expectantly,


    • Did you ever get to the bottom of this problem. I have had exactly the same problems. Have unblocked under the battery and replace the seal around the pollen filter housing and still the God damn thing leaks. From exactly where you describe. I also have never found where the pipe comes out on the other side of the bulk head…

  7. Superb guide. Thank you very much: hopefully this was the problem, and when the (sopping wet) carpet’s dried out, it will _stay_ dried out!

  8. Many thanks for taking the time to put this together, helped me find a bodge solution to unblock the servo side drain with some washing liquid and a bit of contortion!

    ok, I have the random Passat ’02 plate 1.9TDI PD (state Diesel Estate) alarm problem, it goes off yet the lights do not flash, have tried the switch to disable motion sensors which seems to reduce the frequency but the alarm still goes off, does the gremlin know to wait to 03:00 AM ?

    Anyway, chuffed to find this article, gutted that VW design can be so poor and so many people affected. With this article I now know how to remove the battery cover, so easy when you know how, I was able to have a look, and could see a puddle under the brake servo as seen from the drivers side. I didn’t have the time or inclination to remove the battery etc (and did not have the radio code about) so using a torch and some acrobatics in the engine bay I poked about with my left hand to managed to find the drain under the servo, wouldn’t have known where to look without this guide. Problem being I couldn’t reach far enough to push the crud through. Coming back to it armed with washing up liquid on my hand and arm I was able to reach that bit further and find the recess of the drain and push the crud through at which point I heard the water washing through, victory.

    So, I have a temporary fix for the water drain issue from under the battery, I now know how easy it is to do a pollen filter change (mine was also very black having been replaced in a service recently – hmm!) BUT did not find a wet floor under the carpet and the alarm still has random episodes so I think I might need the dealer to see if the can tell which sensor is triggering the alarm.

    • As a result of your ‘shortcut’ solution, I did the same today without removing the battery. With a torch, I found the rubber drain plug. Then, I followed your route and managed to insert my hand just enough to feel the rubber plug with outstretched fingers, gave a push, and whoosh the water drained off in seconds. No more will I need to siphon off the inches of water with a long plastic tube, only to have to do it again the next time it rains. I squirted WD40 into the recesses of the battery tray etc., just to keep at bay any rust which may have started down there. This success even encouraged me to change the pollen filter (only £5.10 on ebay)! Went the day well? Verily. Thanks for the good idea!

  9. Fantastic guide, thanks so much. I have had a minor but very definate wet carpet for a while then today, the alarm game has started! No longer can I keep my head in the sand and hope cars get better on their own – idiot but we all do it sometimes. I’m confident that your guide will fix the leak I just have to get off my butt now.
    One little thought if I may. If you take the battery off you lose the radio code! OK if you know the code, a pain if you don’t. Avoiding it is so easy I couldn’t belive it myself but it works and I found it by acident. If you have a car charger for your mobile just leave a fully charged mobile connected and its enough to keep the radio code alive while the car bettery is off.
    Thanks again and wish me luck with a soggy car in horrible weather, that’ll teach me for leaving it too long. (2001, 2.0L petrol, Auto, 103K)

  10. I see your great job from Spain, I have the same problem in my passat. I don’t know what’s the problem, the rear door or the hole under the polen filter. I’m going to repeat your work.

  11. excellent guide I have the same problem with my VW Passat 05 reg and VW are saying it is not a design fault and all the dealers know the issue and just charge you silly £600 plus amount to sort the problem out. Go to a friendly garage and they will sort it out for you quickly. We should set up a petition to ban all future of VW cars due to the stupid design fault and they should recall all these models.

  12. Boy am I glad I found this website and thanks for the excellent guide. I have an 02 Passat estate – have had water problems before and thought all rectified by the garage some years ago. Last month water n the rear left passenger footwell – soaked up and all was well. However last night the alarm started to play up ANNOYING to say the least. Anyhow following the nest ructions on this page we set to work this morning. We haven’t braved taking the battery out yet – but have removed 3 1/2 litres of water from around the battery and brake cylinder thingy – TOP TIP – we used a long suction pipette to take the water out, together with a section of straw to get under the tight bits. Have just checked the rear carpet and managed to pull up a section – have found the underlay soaking, so will now set too and try to dry it up. We may resort to cutting a section of carpet.

  13. Thanks very much for this made the job of cleaning out the drain holes that bit easier… now onto the pollen filter :)

  14. Thank you very much for such a well-written and researched guide. This was certainly very helpful to me in dealing with my own “Passat Swimming Pool” problems.
    It was getting ridiculous: first the theft alarm would start going off (always at night, of course. . .); the ABS warning would occasionally come on when I reversed; we lost all the interior courtesy lights; the low oil warning came on (checked out – plenty of oil); the central locking became erratic; the electric windows failed. Finally the fuel cap release failed (and on this model, there seems to be no manual override), and we realised that we couldn’t put it off any longer!

    For the most part, all I needed to do was follow the excellent instructions on this page, but there were a few steps that had to be changed for my 03 Passat TDi Sport estate:-

    The bracket bolt is 13mm on this model.
    Even with the rubbery hose/cable assembly unclipped, there was no way the battery would come out. Clearance was limited by a pair of metal pipes clipped to the bulkhead (only about 1mm clearance).
    So I went back to Haynes (last resort – it lets me down just about every other time. . .) where it said that the windscreen wipers and the plastic trim underneath them need to be removed. This produced one of those “WTF were the designers thinking?!” moments, coupled with a lot of stomping around kicking things. I’m sure anyone who has ever done minor jobs on a car knows that windscreen wipers are the creation of the devil. Once they’ve spent a few years on the car, they’re rusted on to their shaft splines. It was possible to remove one of them with a lot of levering and bashing of the spline with a hammer (after leaving to soak in WD40 for over an hour). But the other wouldn’t (and still hasn’t) budged. The only way I was able to proceed was because the plastic trim had cracked between the two wiper mounts, so to clear the battery I only had to remove the one part.
    That part in turn broke as it was being removed. Luckily I was able to re-join the pieces by welding them with a large soldering iron. Not pretty, but effective.

    As the battery is right in the centre of the windscreen and heavy, I found that removing it was best done by passing a strong piece of wood under the two battery handles, then lifting it up and out with a person holding each end of the wood.

    The good news is that I’ve now drained the pool, and as my other half had meanwhile spent an hour or so drying the area around the CCM, some of our electrical problems (locking, windows, fuel cap, oil warning light) have now gone again.
    We’ll continue drying out the under-carpet area tomorrow, and maybe extract the CCM.

    Given that VW’s advertising quite boasts about their wonderful designers and engineers, I’m really annoyed that they could have designed such a turkey this time.

  15. I had this wet footwell problem, found your guide, and followed it…..

    A great big thank you! How I laughed when I got to the end and read how you squashed your plug of muck!

    Mine’s a 54 plate passat and worked fine.

    NB – don’t do what I did and use a brush to push the muck through the drains – it fell in! Luckily it ended up on the drive.

    Seriously – thankyou for the time you’ve taken to upload the advice helping us all out.

  16. With the aid of your photos to locate the drain holes, I was able to bend some wire into a goose neck shape and feel for the holes thereby unblocking them without removing anything !-years of model airplane making have finally paid off

  17. Excellent post …. I set about mine this morning … I’ve got a 54 plate Passat Est and CDL was intermittently working on the drivers door … Though my carpet was not wet to the touch when i lifted the front passenger side and felt the padding underneath it was slightly damp and there was a dew/mist on the floor.
    Luckily my CCM was dry though still sprayed some WD40 on the connections … with a towel i gave the floor a quick wipe …. i couldn’t see any obvious wiring damage / connections looked fine ….

    Ok the main reason for my post …. having cleaned the drain holes (under the battery tray) …. an absolute MUST is cleaning out the channels by BOTH the bonnet hinges ….
    My nearside channel was completely blocked with slit / mud … and it looks like this was backing the rain water up causing it to flow over the seal where the pollen filter housing joins with the body of the car (hence wet n/s/f foot-well)… i got a good handful of gunk out …

    Having checked the drivers side again this was completely blocked …. I found out that the rain water drains UNDER the ECU housing box, so using a hose with light pressure on the screen the water i could see the water was not draining away …. after removing another handful of leaves, slit & mud i used a coat hanger to clear the drain channel UNDER the ECU housing ….. and with the water back on the screen it was flowing down the channels nicely and draining through both now cleared drain holes …

    Fingers crossed this has solved my problem ….

    My advice to people completing the above DON’T just clean out the drain holes make sure BOTH channels are free too ….. because i believe this was my main problem ….

    • Thank you, thank you, thank you. Had exactly the same problem, cleaned out the drains but still getting water in.

      This fixed it.

      Thank you sir, you are a star!

  18. I’ve feel I’ve been lucky with my year 2000 B5 estate as many older cars like mine will have been scrapped due to this manufacturing fault. Shortly after I acquired it I discovered the blockage problem when, after a good downpour, a bucketful of water cascaded over the front wing when going round the first corner. The fresh air flap motor has subsequently failed so I guess some water has got in previously via the pollen filter housing. But no other damp or damage is apparent.

    My ongoing solution has been to make a ‘drainrod’ for the hole under the battery so I can jiggle it to clear debris without removing the battery on a regular basis. I made it out of a strip from a piece of ABS/PVC drainpipe which can be easily heated to get a couple of 90 degree corners and is stiff enough. I guess you could also use two strands of twisted coathanger. Mine comes out of the drainhole, through 90 degrees, over towards the centreline of the car then another 90 degrees and up the side of the battery. A good wiggle every couple of weeks and the occasional flush through with clean water keeps everything hunkydory.

  19. Brilliant guide! Thank you very much. I’m impressed by the photos and your thoroughness.

    Mine is a ’54 Passat 190TDI and the guide was spot on. Eventually got the first rubber liner out, the one under the battery. The other one, the one beside the brake servo, I struggled to remove then realised that it is of a different shape. It includes a tab (not easy to see, as it is right at the back) through which passes a 6mm dia steel pipe, so that rubber liner cannot be removed without cutting it out!!

    Like you I considered permanent removal of both rubber liners but ended up cutting a bit off the end of them to increase the outlet area. This action effectively ruins them as 1-way valves so, in hindsight, I should just have binned them. Incidentally, after I had put the battery back and taken the car to have the new airbag sensor configured at an independent VW specialist, he told he always leaves them out as they are completely useless!

    These rubber liners are a good example of over-design. The designer wanted to create a 1-way valve (quite why I’m not sure since the likelihood of water coming up the drains is pretty remote!) but in doing so compromised the primary objective i.e. to act as a reliable drain.

    Your query: “If you know what this cable is called, can you let me know”
    I asked the indie and he said that it is just a bundle of cables with no specific title.

    Just a very small pont re the guide: I found it a bit of a struggle getting the clips off that retain this cable bundle. Perhaps your’s were more compliant than mine or I was using the wrong technique, but I had to apply considerable force via a pair of pliars to get them to come far enough forward for the clip bit underneath to clear the bodywork.

    By the way, after sorting the drains and drying the car out I purchased a replacement airbag sensor on-line for about £25 but it could not be configured by the indie! I then had to bite the bullet and buy new from VW at an eye-watering (excuse the pun) £145. All went OK then and car back on road. It seems that replacement electronic parts need to match the VIN not just make/model/year.

    Final thought: Just shows what a complete con so-called Service Schedules are! You get charged about £300 to change oil and a few easily accessible filters. Most of the rest of the items are there only to pad out the list and take no time at all to perform! If they were genuinely interested in maintenance, routine clearance of these 2 drains would be a must.
    Keep up the good work!

  20. Thanks for an absolutely brilliant guide, written in an entertaining and ‘everyman’ sort of style. I don’t know what your day job is but you are wasted on it. I am thinking of getting a Passat and the one my mate at work had was plagued with the problem you have addressed. It put me off then but it won’t any more. Incidentally, it’s nice to see a photo guide where the mechanic has dirty fingers. Never trust a mechanic with clean mitts and run a mile from one who has manicured hands.
    Thanks again for a really great guide.

  21. Following my personal trip to the Passat swimming pools on the driver side of a ’55 Passat estate, I’ve managed to clear the drain holes and the side channels. It just remains to dry everything off and the fingers crossed… Many thanks to you and the others for most helpful advice.

    I also had trouble getting battery out, but a bit of perseverance paid off.

  22. Went to town one bright morning and heard a sloshing sound inside the car. Oh yeah forgot to say that the heavens had been open for quite a while for the last few days. After the console lights started going funny and the automatic transmission decided to get stuck with “engine workshop” flashing in the dash’ it left me with a bad feeling to say the least. In the drivers side and rear footwell were those dreaded 4″ puddles. VW were not helpful despite having serviced the car with them for 10yrs. Why oh why did they not check this simple problem and hence prevent it? Only the great fairy in the sky knows in VW’s infinite wisdom. Thanks VW for all your trouble free motoring fun…NOT. If i wanted a swimming pool in my car i should have the right to say no?Wrong as VW believes your driving pleasure needs to be tested from time to time. Anyway those folks in the states who were not pleasantly amused filed a class action law suit against VW for something like a paltry sum of 62 million $. But oh no, VW rather than settle this fiasco decides to appeal and drag this through the courts, as it’s evidently more moral to pay the lawyers. It seems American consumers are better protected? Read the law suit in the following link:

  23. Spot on thanks. This was the exact issue on my Audi S6, so I expect this will apply to all A4′s, A6′s and allroads too!

  24. Great stuff great guide, I’m sitting with the same problem the con rods ended up getting messed because of that. I’ll clean it up. How often if necessary should one repeat the procedure?

  25. Good guide, just a couple of points that ‘big black thing’ isn’t the brAKE master cylinder but the brake servo. The cable in step 5 is the engine loom.

    Another thing that can be done to put the module out of harms way is take it out of the footwell & move it upto the bulkhead. Theirs plenty of room & the cable’s long enough too.

  26. Very useful article. I followed it to the letter, with perfect results. My only difficulty was removing the wiper arms, for which I made up a simple puller from a scrap of oak, two M8 roofing bolts and an M8 center bolt. Picture is here:

  27. Thanks This and other pages on this subject and CCM problems are manna from heaven.VW Australia is the same world wide.Must be something German companies don’t do. Except that they made a stuffup on the design. Be it cars or chemicals(drugs for morning sickness) Once again tar Regards Dene

  28. Great tutorial. I did mine in under an hour and I haven’t done any jobs on a car for probably a decade or more!

    Hardest part was removing the three metal clips.

    One tip : If your footwell is really soaked, get yourself a carpet shampoo machine with an upholstery / stairs attachment. Use some duct tape to adapt its hose to a half inch diameter tube (local homebrew store or DIY store) and use that to suck water out of the car. You can insert about 1/2 tube where the carpet comes up near the heating ducts under the front seat, or near the centre tunnel.

    I suck about a gallon of rain water out of my footwell using a VAX ! (Metric gallon too!)

  29. Great instructions many thanks. Being an ex vwdub mechanic it only took about an hour to sort the problem and bang on the area under the battery was about two inches deep with water. To any one else with this problem, don’t waste time trying to siphon the water out, just gently poke a finger through the rubber and hey presto the water runs out.

  30. Wonders of the web, used the guide was only a blockage by my pollen filter but all the gunk removed new filter purchased and car dried out. Many thanks for taking the time to do this really usefull guide saved me a trip to the garage and lots of money. Will keep a close eye on it and flush it out regularly.

  31. Prevention is better than cure in my case…. (Passat 2005 – 05 reg)
    Thanks very much for this excellent guide, I carried it out step by step and eventually found & cleared out the two grommets which were both full of dirt and bits of leaves and also the complete area under the battery tray is now clean. I’m sure that I’ve just narrowly avoided the problems associated with this, as already mentioned by another poster do make sure the water runs are cleared from the roof down and also the areas near to the bonnet hinges as these were absolutely full of gunk as well.
    Do be careful when replacing the battery though, as I managed to snap a small section of this plastic off (the piece attached to the windscreen with small slits to catch leaves and with the wiper holes) although annoying I have managed to super glue and effect a small repair to this area.
    One good piece of advise mentioned here (thanks to that person) is to connect a fully charged mobile phone inside the car, this does hold enough power for the radio and prevents the need for entering codes and all your radio stations of choice again. Thanks again

  32. Excellent thank you for taking the time to detail the procedure required to sort out the leakage problem and check controll module for possible damage.No doubt water getting into the passenger footwell then travelling to rear footwell is the cause of my alarm sounding at 3am.I have dried everthing out controll module thankfully seems okay.I have a vw passate 54 plate 2ltr petrol.I cant find the drain hole shown under the servo is their one on this model.No problem finding the drain hole under the battery carrier.Once again thank you.

  33. Just a quick follow up to this post.

    Drained plenum chamber, dried out the electrics but still had a problem with random alarm going off. Finally worked out what was going on when smoke came out of the alarm siren (bolted to the battery carrier).
    It had filled with water and fried the electrics inside.
    Replaced by secondhand part from internet (stealers wanted £95) for £10.

    All fine now.

    Once again, many many thanks.

  34. I have had wet carpets for a month and was about to get rid of the otherwise reliable 02 Passat and found the culprit in the blocked hole under the battery. This guide is the most comprehensive I have seen, followed it and no more blocked hole.. bring on the rain for a propper test.

    A certain tip is to use a hose to syphon off the water from the battery tray area, i got rid of 3-4 litres of water this way.

  35. An excellent and well written guide. Thank you. Why the hell don’t VAG do something about this!!!! Ps after fixing this leak it turns out my B5.5 is also leaking through the door where the mounting plate has lost it’s seal. Ho hum

  36. Despite what looks like a comprehensive redesign in the 2005+ models I am still getting the problem in my 09 model – anyone know how to cure that please?

  37. So, I have a 2001 Passat. We found one drain hole under the master cylinder, didn’t ever take out the battery to see — is there another? Poked the one drain with a wire, the gasket and hose disappeared and didn’t end up on the driveway. Is it inside some where and will it do harm? Haven’t tried to fish it out, should I have a shop find it? Do I need to replace it? ARGHH, thought about selling this car from day one and VW was impossible to work with from the start.

  38. hi i have just looked through the website and have got to say what a good idea the way it is put forward with the brief paragraph about what to do and a picture. i have just got a vw passat 1.8T 20v mutha and had the problem with the drainage and have looked all over the net stumbled on this and have just finished brilliant website.

    thankyou very much for taking the trouble to do this and help loads of vdub owners.

  39. A really helpful step by step guide, thank you for taking the time to do this. I’m yet to see if it has solved the problem but looks promising as there was half an inch of water under the battery when I started and as I poked the drain holes through it drained out.

    So much water has come in over the last few months the car has felt more like a leaky boat!
    Will be keeping my fingers crossed but am hopeful & wanted to say thank you.

  40. One of the best how to’s ive ever came across!It is a big problem with passat’s With angry neighbours threatening to smash up your car if you dont stop that bloody alarm!! Great job

  41. Just followed your brilliant concise instructions to clear the drain holes under the battery on my 2003 passat. The most difficult part was removing the battery but brute force and ignorance eventually prevailed. One very very minor point it is a 13mm socket not 14 to remove the battery clamp. Thank you very much

  42. Excellent helpful guide, I have a 95 Passat Est, water in rear passanger
    footwell, Not mechanically minded but gave it a go and with a little problem releasing LHS. Battery brace ( tight) managed and felt very satisfied after about 1,5 hrs worth of work. removing battery was a must for me and both holes were blocked. Well done for supplying this excellent guide.
    Thanks John

  43. just done mine, easy, i had a receipt from previous owner including modified VW pollen filter seal, word of warning folks.

  44. Thanks. You’re a legend- that was extremely helpful, and I appreciate the extra mile you went to post all this.

  45. Pingback: Done today something EVERYONE should go do!

  46. Great article with photos and everything. Same problem with an Audi Allroad (2000). Nearly identical and, thanks to you, the problem was resolved in 35 minutes. Thanks for taking the time to share knowledge and you experiences. Well done

  47. Hey there. Super article. The passenger side floor of my Passat was drenched so I googled it and found your site. When I removed the battery cover I found about 2-3 litres of water sloshing around in there and sure enough when I checked the drain holes both were completely clogged.
    Well done again and thanks for the help.

  48. A truly brilliantly written article. It was my son’s Passat so I’m not sure about B5 or B5.5 but guess from a comment about B5 with regard to upto 2000 suggests that B5.5 is a newer, post 200 model.

    To sort this problem, we needed a 13mm socket just in case someone has to buy a socket just for the job.

    The car is a diesal and my son suggested that the battery is slightly larger than for a petrol engined car. Whether or not that’s true, we had difficulty removing it from it’s location – thus the suggestion to remove the trim for the windscreen wipers – but with a bit of gentle force we were able to move the battery towards the pollen filter over the lip (mentioned in the article) at the pollen filter end and then lift it out.

    We also had trouble with the engine loom clips. At last I could use my 40 years of engineering experience! In the same vein as the way the article was written by giving the detail, note that the end of the underside part of the loom clips curve downwards away from the underside of the horizontal part of the engine compartment panel. Use a flat (wide but thin) screwdriver and put the flat against the front side of the panel with the side of the screwdriver blade up against the underside of the horizontal part. Push the screwdriver towards the clip so the flat is gently forced between the front side of the panel and the end of the clip. Now twist the screwdiver (as if dealing with a screw) to move the clip away from the front side of the panel. It may be helpful to do this from both sides of the clip. Trying to keep the clips horizontal is also helpful. When replacing the loom, try to push the loom back down behind the panel prior to pushing the clips back into place.

    We had some fun with the sounder. Having delved in we found that a slot in the sounder bracket located into the battery tray and by removing the connector from the sounder were able to gain easier access to the offside drain (offside due to right hand drive vehicle).

    One thing to note. We had the impression that viewing the drain holes was going to be obscure having removed the battery and done other bits but they were fairly obvious.

    It might also be worth noting that we found over 5 litres of water under the driver side carpet (right hand drive vehicle) but drain holes were crud filled even though no water was found in the plenum/battery space. I presume if water was in this space then possibly more than 5 litres would be under the carpet. On top of this, the 5 litres does not include the water saturating the carpet. Kiss goodby to using a hairdrier to get rid of the water and don’t assume that if the carpet top surface feels dry there will not be water underneath it.

    For the uninitiated, a plenum is a space connected in some way with a gas (which could be air). In this instance it refers to the space (arguably erroneously as the gas connection is questionable) where the battery, servo, alarm sounder, problem drain holes etc. are located.

    Moving into the cabin of the car gave some surprises even though we knew the carpet behind the driver’s seat was a little damp! We were expecting to find an electronic module under the passenger side at the front but noted that there seems to be a similar module at the passenger side – it’s a right hand drive vehicle.

    We intended to lift the carpet to determine the water quantity problem. We started with removal of the seat. As a precursor, due to the air bag in the seat the battery was isolated (NEGATIVE DICONNECTED FIRST) and we earthed ourselves to prevent static problems. Having removed the seat slider covers in the rear passenger footwell, this was easy – move seat backwards then undo two nuts under the front, to finally (rather than fiddle with snipe nosed pliers) sit on seat, lift adjustment lever, slide forwards then gently backwards and the central rubber is likely to exit its hole but avoid going too far back and damaging the carpet in the process.

    We then removed the screw holding the covering forward of the front door – a nut fell out – allowing us to ease the carpet out from under it and then lifted the trim running along the door sills. Lifting the front edge of the rear seat allowed us to pull the carpet out from underneath it. We were able to sufficiently to determine that the floor under the carpet was a reservoir. We actually sponged up about 5 lires of water without having had any electronic problems so I dread to think how much water is sloshing around if the electronics is affected.

    Due to all this water we decided to attempt to lift the carpet. Very bad idea!!! The carpet flows over the central front to rear hump from near side doors to off side doors. At the front it seems to go under the dash and behind the central console. I suspect that even if we were able to remove quite a lot of the central console bits and pieces plus door sill trims, seats, etc. etc. etc. we would still not be able to lift the carpet. In our case, the weight of the water held by the caret would probably require the the use of a crane!

    However, just in case someone else wants to try this for themselves, here goes with an explanation. The car is an automatic so needs to be in neutral for removal of the gear stick surround covering, having removed a screw from either side at the front. The rear part of all this central stuff can we removed by undoing two nuts towards the rear under the central arm rest and one towards the front left (looking forwards). These were accessed by removal of the tray having opened the arm rest. It is very tempting to remove the covers which we found someone had done before us, rather than removing the nuts. The cover is held in place by screws to the framework under the arm rest and comes away with the framework, the rear ashtray, the cigar lighter, etc. We also removed the left foot foot rest (no clutch – automatic) which has a cover on the pedals side and

  49. Oops! This is the extra bit. Seems I inadvertently clicked on “Post Comment” before I checked for errors or completed the details. In the first paragraph above “post 200″ should be “post 2000″; the twelth paragraph has “caret” which should read “carpet” and five lines further on “central stuff can we removed” should be “central stuff can be removed”.

    Sorry if it’s long and detailed, but hope it is of benefit to someone.

    In the last pararaph I was going to write: … which has a cover on the pedals side and is held in place using pozidriv screws.

    To continue:
    Having removed all the arm rest stuff, the covering for the gear stick area, the door sill covers, the foot rest and of course the seats (removing both to give us some room as they come out so easily), as well as loosening the cover forward of the front door and the rear seat, we were able to prise up the carpet, remove the electronic module, drying its base of the drips sustained in the process of removal, and sponge up the water. Subsequently, we have the carpet in an almost vertical position against the central hump, having pulled it out from behind the pedals and from under the rear seat. The “bend” in the carpet from coving the floor to standing vertically is a couple of inches off the floor and dripping profusely even after numerous attempts to squeeze out the water. We are now using a dehumidifier to attempt to dry the carpet. This has been on (upto now) for about six hours and has sucked almost 2 litres out of the car atmosphere. I have also just now squeezed several spongefuls of water out of the carpet along the bend.

    The upshot of this seems to be not to assume the water can be sucked up with the carpet in place on the floor and don’t expect to dry the carpet in a short while with a vacuum cleaner or hairdrier. Unless you know there is no water under the carpet whilst the carpet shows signs of having been wet it seems you must assume there is water underneath it. I would also not expect to have a dealer sort the situation in a day – and this is not a sleight against dealers or garages. Having observed the problem, the carpet/underlay thickness and the pratical possibilities of simply removing the water, I suspect it will be many hours or even a couple of days before the carpet can be considered to be dry.

    I hope this is useful to some as it seems this problem of water ingress due to something so seemingly insignificant can have significant implications. I fully appreciate why one respondent wrote that he was thinking of getting rid of the car due to the problem.

  50. As a follow up to having used the dehumidifier here goes: we sponged up all the water on the floor and squeezed as much water as posible from the carpet/underlay. This gave us a scenario that most people may well find if the problem is not known about such that leakage into the car has been occurring for a prolonged period especially as the water tends to pool under the carpet initially rather than be in or on the carpet. We had the dehumidifer on permanently for about 60 hours, sitting in the car with all windows and doors closed.

    After the carpet dried out it took us about 2 hours to slowly and metodically refit the carpet, door sill trims, central hump euipment and both seats. However, it may be worth mentioning again that this problem had obviously occurred previously to the vehicle as several of the plastic cover had damaged fixing points such that we were able to just remove these covers.

    All the best to those who have to work through this problem.

  51. Thank you for this excellent article that explains why i’ve been having electrical problems with my 2000 Passat 3b5 TDI. I shall set to the CCM and wiring loom this evening! Just thought I’d add that another source of water ingress into the car can be from inner door skin leaks. The inner metal door skin is fixed to the door itself with several bolts and sealed around the edge. The inner skin needs to be removed if you have to do any work on the door locks, lock electronics or window mechanism. BUT once you have removed the inner door skin the seal is knackered and rain runs down the inside of the skin and out through the plastic door card and into the car footwells. So when replacing the inner door skin after working on the doors I would advise replacing the seal with silicone (potentially a messy job but it will save you a lot of trouble in the long run). Another thing to check for is that the two large plastic bungs in the inner door skin (the ones you remove to release the bolts holding the window glass to the window winding mechanism) are in place. I recently bought my passat and noticed whilst driving in heavy rain, water running out of the bottom of the passenger door. It turned out the previous owner had neglected to replace the bungs after working on the door! They are there for a good reason. Hopefully once i’ve checked my CCM and wiring loom my interior lights, alarm and possibly reversing lights might start working properly again!

    • Why would you seal that with silicone? Doing so would make it VERY difficult to remove, if someone needed to open it up up again further down the road… If you use butyl rubber, it can be removed again using a heatgun…..

  52. Thankyou for this amazing article. Straight to the source of all my problems. The battery tray was level with the water underneath it! Had to go as fars as removing the passenger seat out of my audi 1.9 tdi estate x reg. really was wet down there in the harness loom area. Took whole carpet up on passenger side and sponge and bucket to the fore. That foam holds a lot of water.

  53. I had a flooded Passat due to blocked drain holes under the battery shelf, I did not have the time to follow the dismantling instructions but managed to clear the obstruction. I found a length of flexible glass fibre rod about 2 mm diameter, possibly from a fibre optic cable, and slid it under the battery holder from each side and ‘puggled’ it around in the area shown in the photos. Eventually the water level went down, I had obviously cleared the muck away from the drain holes. I suggest this as a temporary fix for this problem. Any form of rod could be used as long as it is flexible and unbreakable, maybe the old faithful wire coat hanger which any self respecting engineer should always have to hand!

  54. I have a b5 passat you dont have to remove the battery if your hands are small enough, i managed to squeeze my hand through and pop the bung out, took 20seconds if that, i decided to leave it out as it will only fill up again.

  55. Just wanted to say thanks for such an easy to follow and straight forward guide to fixing this problem. I can’t thank you enough.

  56. This is an excellent guide, I came across it while searching for an alarm problem. Further to earlier posts, I have a 2001 Passat and the because of water problems, the alarm was going off frequently, I had my auto electrician take a look, but he couldn’t find a problem on the day he tested it, but it still continues to go off at odd times. I eventually got over the problem by un- plugging the audible part of the alarm which is in between the brake servo and battery. There is one nut on the side and you can lift it out far enough to unplug it. I have covered the connecting plug with a plastic bag to stop any water getting into it. The unit is now in my shed which is the best place for it. By unplugging this it DOES NOT compromise any of the other electrics on the car.
    Now I can go back to sleep.

  57. Passat 1.9 2003, having just bought this car, I wasn’t prepared for gallons of water under passenger seat, and seat behind, didn’t occur to me to check this.
    Having found this website I immediately pulled off battery cover and tray, to find underneath bone dry, and drains clear, but what I did find was lots of mud like gunk under passenger side bonnet hinge, and beside cabin filter case.
    Using a small length of co-axial Ariel wire I began to poke the gunk out from under hinge, with cable being bendy but strong, was able to get most of mud out, spraying engine degreaser on the rest of it turned it to mush, then a cloth to get it dry.
    Pouring a cup of water over the windscreen, it was a relief to hear it drain onto the ground.
    Hopefully this has done the trick, taking ages to mop up carpets, will have to get a wet and dry Hoover

    • Update on last post.
      After next heavy rain was back to square 1, passenger side front and rear flooded.
      So took off pollen filter housing to see if that was problem.
      No obvious splits or tears in seal, so cleaned both filter housing and where it touches car, then out with the silicone gun, went to town on both surfaces, refitted cove with big squelch, there’s been no rain since, and have been too scared to pour bucket of water over screen to check, will update next time there is rain

  58. Hi Bruce, have you had any work done on either of the passenger doors recently? I had a similar problem to yours and it turned out to be the seals on the inner steel door cards. The mastic used by the factory only lasts so long, and if its been disturbed by work on the doors (locks, window motors, runners etc) 9 times out of 10 it will no longer make a water tight seal – so water will run down the interior of the door, through the seal and out of the bottom of the door inner card into your foot-wells. My brothers are both mechanics and whenever they work on VW’s they replace the seals with silicone. This cured my leaks immediately. Also check you door window seals – the ones covering the join between the top of the door outer skin and the window glass – if these are corroded or missing, water will get in. Once you’ve cured your leaks – you’ll need to sort your wiring loom out too, There are very good articles on this already – and if you’ve had serious water ingress – your loom will soon be causing you no end of grief – best of luck – Rory

  59. Hi Rory thanks for reply.
    Did pour water over window and door when it was open, it seemed to all come out drain hole in bottom of door, haven’t done it closed though.
    You mention seal inside door, is this seal obvious when you take door card off, inside of door is bone dry, have checked when cars been wet.
    Having said that, there is an annoying rattle from front door passenger side, door maybe it has been worked on and stuff disturbed. Will look into this as well
    Thanks Bruce

  60. Thanks for this guide, it has helped me on two cars now. First was a cheap B5.5 Passat just like yours that had newspaper stuffed under the carpets and a CCM in a plastic bag but the bungs were still in place. I then bought a 2009 SEAT Exeo and found that they use exactly the same design as this, so I can only presume the B6 & B7 Audi A4 are also affected. Unfortunately on these cars, the water gets in on the drivers side where the ECU sits, and causes havoc to instrument clusters, CCM, TPMS module and the ECU itself. Luckily for me, I caught my Exeo early and no harm was done. I hope other people manage to find this on Google and sort this out before it becomes costly.

  61. Just as applicable on a warm dry & breezy day in 2018 !
    Found this guide invaluable with confidence in diagnosing & fixing the cause of interior leaking; found both drain holes completely blocked.
    Many thanks for putting (& keeping) this up, however long ago !

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