Fixing Your Audi A6 Water Leak (Video)

Rain has dominated the Shenandoah Valley during the last few weeks. I can appreciate the value of precipitation, since rain = good water levels which = more kayaking excursions. However, the precipitation hasn’t been very kind to my 1999 Audi A6 Avant.

A few weeks ago, I noticed a water leak in the Audi. As I drove uphill, water came rushing through a vent near the passenger side floor. I figured this is one of those problems you can’t really ignore.

Instead of dropping $150+ to have a dealer fix the problem, I decided this was something I would try to fix on my own. The good news for me is that I fixed the problem in less than an hour. The good news for you is that I’m a nice guy and I took some raw video of the process.

I won’t make any guarantees, but this video should help Audi owners who are experiencing similar problems. When you’re done fixing your water leak, feel free to send me a check for the difference.


Add yours
  1. 1

    hi, i have audi A6 1996- we had strom in NY and my passanger seat is full of water. It the car 3 day finally was able to start it. But now i have issue with transmission, it wont change gears. While im driving gets stuck in 2 gear. After reading few post online about this issue, i learned that there is transmission controll under pass seat. Does anyone else has same issue and how did you fix the problem?


  2. 3

    I read few posts and im having the same issue. There is leak on the back doors but i am unable to find it. Everytime rains now under passanger seat is filled with water.
    i took the seat out and pushed the carpet to the side still unable to find the problem. also i check the sunroof and seems to be fine.

    please anyone who has had this problem and was able to fix write me at

  3. 4
    Sidney B

    Thank you so much for this Josh. I opened up the battery compartment like you advised, and it was full of water just like you said. Only difference was that I sucked it all out with a shopvac, sted of pulling out the battery and the plug.

  4. 7
    Dale Dass

    Waw! Dude much relief now that i know. Heavy rains a few weeks ago and we met a 1 inch flood on the floors… Total confusion especially where the door glasses were up.

    Thanks man,

    Blessings from the Caribbean

  5. 9

    You are a f—–ing legend, I have an A6 and with exactly the same problem, but i am in the alps and its below 0 so even worse with water in car!! followed your instructions to the letter and you were right. If you are ever in the alps i ow you a big drink


  6. 10

    I have got the problem in the back seat on the left. What can be the problem and the possible solution.

    Thanks for advice.

    Dharamjeet Bucktowar

  7. 11


    I’m not sure about water in the back. Several other owners have mentioned this as well. Could it be getting in through the sunroof?

    Either way, I don’t know what the solution is for this problem. Keep searching Google and maybe you’ll find something.

    Best of luck to you,


  8. 12
    Sean Owens


    a tip that might save you about 2 hours on this task. This applies to later a6’s from 2005 on that have the battery in the boot ( trunk )

    Seeing as most of the blockage is usually gunk or a stray leaf. So its debris that is very easily dislodged.

    Strighten out a wire coat hanger,

    make a right angle bit at the end about 6 inches.

    now open the bonnent in the area where the battery is on the video poke the bent wire around in the swill of standing water with the object of finding the drain hole and pushing through it.

    You will know when you have cleared the drain hole because a rush of water will drain out. Depending on the amount of water it night take 1 or 2 minutes to drain.

    This method saved me dismantling the air con and heater unit. Anout 2-3 hours work and heart ache.

    I hope this helps you all.

  9. 13

    I see you remove the plug and the water drains from the pan. Where does it go? And … if it goes to the ground without entering the vehicle … why would I replace thhe plug?

  10. 14

    Hey Bill,

    There isn’t actually a plug. There’s a hole that gets plugged up with debris. Once you clear that out, the problem is fixed.

    Have fun!


  11. 15

    This is great!! Thank you so much for posting this! I was going to bring my A6 in for this problem and now I don’t have to. After searching the problem within minutes I saw this is a widespread problem and shame on Audi for not taking responsibility. When my not so mechanically inclined boyfriend gets home this will show him how… And if not I can do it! Thanks again!

  12. 16
    Glenn Hooper

    I spoke to an Audi dealer about this problem and apparently their solution to the problem was that at each service when the car is on a ramp they poke it out with a long rod while underneath the car rather than having to remove the battery. I thought about drilling a hole in the side of the ‘trough’ so at least if the drain hole gets blocked then an overflow system would prevent it draining into the car but haven’t had the courage to do that. This problem also occurred on a Vauxhall Cavalier many years ago but that was much easier to solve.

  13. 18

    Thanks so much – I called the dealer and of course got the “bring it in” recco. So glad I woke up at 5 am and searched the web – and was led to your brilliance. Great on camera voice and instructions, and love the fact you did the prep work in advance of shooting. Thanks a lot.

  14. 19


    Glad you found the video useful. It hasn’t launched my voice-over career yet, but it’s saved a few people some money.


  15. 22

    Great video! We have cleaned out the 2 drain holes beneath the battery and we’re still experiencing water draining into the passenger side (by the cupfuls…we live in the Pacific NW =( It was time to look further. More debris was removed from an area beneath the driver’s window. A channel that drops down into the battery drain holes had clogged up with dirt and pine needles. After cleaning it out thoroughly, we wait with anticipation for the next deluge to see if that acutally resolved the leak. So far, so good!

  16. 23

    help, my electrical is going nuts in my audi, i had water under the battery and on the floor behind and under my drivers seat, inches of it with the major rain we have had, all windows and sunroof has never been opened, had the car 2 years and now it has major rain issues. where is it coming from and how do i stop it. allie

  17. 24

    Hey Allie,

    Try the steps in the video first, as cleaning out the plugged drainage areas seem to solve 95% of the issues. If things get or got too wet, there may be electrical issues that you’ll need a dealer to address.


  18. 25
    Edson Ferreira

    Freaking awesome mate!!!
    Worked for me and you just saved me some money !!!
    GOD bless you and your family 🙂

  19. 28

    Thank you sooooo much for your video Jwal ! I just finished clearing out the plug on my 2003 A6 thanks to your very clear instructions. I really thought I was in trouble though because after driving in a heavy rain yesterday, water started to come in the passenger side and when I tried to accelerate the engine faltered and billows of smoke (steam) came shooting out of the tail pipe. It seems that the well was so full of water that water was being sucked into the engine through the saturated air filter. I also wet-vaced about 3-4 gallons of water out of the interior. I hope this doesn’t lead to other problems by all is good now. Thanks again. Chris

  20. 30
    Steve Kirk

    Exactly the same on my A6 Avant once cleared then only had to dry out the carpets, maybee just one thing to remember before taking out the battery make sure you have the “Safe” code for the audio system as you will need to put this back in to get the system working again.
    Otherwise great video exactly the issue and good description as well.


  21. 31
    Ralph Selby

    I’m working on the same Audi problem – but with a twist! My water emerges under the drivers seat (on the right in a UK car) through a black plastic tube which terminates in two outlets. The rear passenger footwell is filling to the top with water. This seems to have started just after I had a new battery installed last week. The garage didn’t report any water uner the battery at the time and I’m wordering whether there might be a secondary cause of this water flow in addition to the outlet under the battery.
    We have heavy rain here in the UK at present (01.10.2012) so I’ll look to tackling this one when the weather improves!
    Thanks for any comments

  22. 32

    Hey Josh….Thanks for your video! Great job, very clear & easy to understand.

    I am a trained automotive technician who happens to have recently purchased a 1998 Audi A6 Quattro. I love everything about the car except the non factory passenger side foot bath that seems to appear whenever I drive in a heavy downpour. My girlfriend & I were picking up her grand daughter one rainy afternoon from the bus stop and on our way back home her grandaughter exclaimed that her feet were getting wet…..I was driving on the freeway at about 35-45 MPH in a heavy downpour (hence the slower speed) and my girlfriend looked back & sure enough, water appeared to be entering the passenger compartment at the door pillar between front & rear doors at the botton where carpet meets plastic pillar cover. I have wet vaced it out but carpet is still damp & and I am not sure if it also comes in during rain storm without driving. I do however have an issue now with the automatic transmission in forward gears. It starts from a stop in “Limp in mode” which seems to be High gear…No pick up from dead stop to 30 or so, then it goes pretty well, ’till i have to stop again, then it’s like I’m driving a Prius up a steep incline from a standing stop (about as much “git up & go” as a John Deere tractor in granny low). I figure the auto transmission control module under the passenger seat carpet is still wet, although I did change the dash cluster after the rain storm but prior to my test drive after sucking water out of interior. The dash cluster I installed was from a 1999 A6 (1 year newer) due to the LCD display not being readable for driver info center. Result was that LCD display is slightly easier to read, but even though the dash came out of a newer A6 with auto transmission, it now will not let me start in “P” but I have to shift to “N” to start & the display says I need to push in clutch, so I am inclined to believe that the wiring is somehow changed slightly from 1998 to 1999 models. I am going to swap dash cluster back to my original to verify whether it is the cluster or the moisture in the tranny control module causing my issue with transmission gears & I will post more to this thread at a later date. Thanks for your video & I hope it helps a lot more people. Sincerely,


  23. 33


    This video has just saved me £150 in garage fees.
    For the guys who said they have water in the rear passanger footwell, this could be the same problem. I had water in the front and back on the passanger side. It seems that when I parked with the front of the car pointing up hill, all of the water collated in the rear footwell.
    When I followed the instructions on the video, I foulnd about 9 inches of water in the battery compartment, which I found really easy to remove.

    Big thanks to JWAL great video and instructions.


  24. 35

    Not a Good Friday afterall…So this past Friday I was supposed to hit the road in my A4 headed to my mom’s for the Easter weekend and my car won’t start and nothing was working…I had to use my key for the first time to unlock my door.

    I called AAA for a boost and once the battery got a kick the car started but the alarm was sounding off and won’t stop until I turned the car off. So then when I restarted the car it won’t restart without another boost. I drove the car to the shop. They figured the power was wacky because the battery and alternator were bad. So they kept my car over night replacing both items. When they restarted the car it fried the both new parts.

    Apparently water got into the computer (located on the floor under the drivers seat (brilliant!) and into the fuse box. I have absolutely no clue how this happened as everything was closed. The insurance company is going to take a look tomorrow and I’m hoping this is not going to cost me a bloody fortune. Not very smart engineering if you ask me, but I guess every car has their faults. Oh and the dealer could care less…they won’t take my car without an appointment. Not helpful.

    Thanks JWAL for posting this…it was nice to see that I’m not the only driver with this problem. 🙂

  25. 37

    I’m definitely going to check it out. Thanks so much! I already started composing a letter to the CEO of Audi, but let’s see if this helps me. 🙂

  26. 38

    my a4 had the same problem but a different solution. the sunroof drain connects to a tube that goes thru the body and drains near the wheel well. the sunroof drain was not connected to the drain tube so all the water was going into the back seat floors. to get to the connection that failed you need to dissassemble the seatbelt coil and the handles that are in the headliner area, and pull the headliner apart to expose the spot where the sunroof connects to the drain tube, right under the sunroof itself. voila…not connected! wtf? the sunroof only slips into the drain tube and is not secured or glued in any way ( at least mine wasnt) mine is now glued together and watertight….oh yeah, look up the class action lawsuit details, even though the compensation window has passed…they only pay for documented carpet cleaning costs anyway

  27. 39

    Hey Reed,

    Thanks for sharing. I know that past visitors had inquired about water in the back seat floors and I didn’t have any answers for them.

  28. 40

    AuAudiless, my insurance company just called my car a total loss for the same reason. We had a tornado come through last week, followed by a torrential downpour, resulting in about 6-8 inches of water on my passenger side floorboard.

    Does anyone know how I could salvage this car if I wanted to? All this water impacted something that made many warning lights come on and lock up my transmission so I cannot put in in drive. Is there a control module or something that can be rebuilt? If so, I might ask my insurance company to let me buy it back from them. I love my Allroad! Any help would be appreciated. Thanks.

  29. 41

    Problems if it leaks:

    1. Sunroof
    2. A/C Drains
    3. Blow out all the leaves inside the car in the side of the black rubber blow it out with tire pressure or high pressure.
    4. Out of balance regulator in the window. If u recently your car tinted.

  30. 42

    So, I had water get into my allroad thanks to plugged drain by the battery. It apparently fried my TCM. If I replace it with a used TCM with same part number, will that clear all the crazy codes I am getting? I dried out the contacts on my TCM, which allowed me to drive my Allroad today, but it eventually failed and my new battery died and it wouldn’t allow me to charge it and drive again. Wondering whether to call this a total loss, or replace the TCM with a good one and hope for the best? Any help would be greatly appreciated!

  31. 43


    Unfortunately, I don’t know the answer to that question. Sounds like its worth the experiment, but you might want to check with someone more qualified than me before making the switch.

    Best of luck to you.

  32. 44
    Jeremy Scott

    Jeremy, I had the same problems on an Avant. I needed a replacement TCM (which sits under the passenger seat). Works fine now but…the damp issues hit me in winter with rain and now again in summer with air con drainage.

  33. 45

    I was happy to find your information about causes of the massive amounts of water leaking into the floor on back and front passenger side of my 2004 A6. However, we checked the area under the battery when we had the leaking problem and no water was under there and the drain was clear. .

    However, it occurred to us that we had just gotten a new windshield installed about one month ago. It appeared that there was not a good seal at the bottom of the windshield on the passenger side. To test this we poured two gallons of water onto the windshield there and the car mat on the back passenger foot well became wet again.

    I did not have it installed at the Audi dealership, maybe that was a mistake.

  34. 47

    on my audi a6 2005 2.7 , i have on the back driver side about 10 -15 l of water ,. , there is a lot of water , ,,i drill same holes on the floor to remove the water, but there is a leak samewhere,, batery is on the trunk , but i am gonna check for leak in the front underneath , another issue is the clutch ,made from lukas and sacks this is what audi is using for all cars , but short life clutch will go around 70000 mile to replace this car is too expensive to maintain , not like mercedes ,bmw -long life

  35. 48

    Slightly different problem with my 2005 Allroad. Water stains on the ceiling liner near the back hatch and damp carpet back there after a heavy rain. How to investigate and remediate?

  36. 49

    Thanks for your help. You are a nice person , thank you. My husband is going to do this in his Audi. The car is in the garage. We cant use it . It is about 3or 4 inches of water in the floor.

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