Audi A4 Problems

Various Probelms Caused by Clogged Plenum Tray Drain on Audi A4

Problem Description and Possible Solution

Clogged drains can allow rainwater to accumulate in the plenum tray (at the base of the windshield). The water may leak into the vehicle's interior, brake booster, or electrical components, which can lead to major problems. Our technicians recommend keeping the tray clear of leaves, pine needles, and other debris.

(37 people reported this problem)

Audi A4 Vehicles With This Problem

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Average mileage: 101,772 (58,000–190,000)
14 model years affected: 1996, 1997, 1998, 1999, more2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2009, 2010
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Viewing 1-17 of 17 comments
After a fairly significant rainstorm, my Audi had water throughout the interior with more water leaking in on the floor of the front passenger area (all windows and sunroof closed tight). When the car was started, it initially started operating only to stall and no longer go into gear. After it was towed to dealer, they could not figure out what was happening. After I did some online research and reported the drain clog issue that so many people have apparently experienced, the dealer then acknowledged the issue of the drain and said that perhaps the water had damaged the transmission module . . . after another day, dealer reported yes that the drain was clogged, the transmission module was fried and they would now fix the drain, replace all interior carpet and the transmission module for a mere $4,800. Since we bought the car used (1 month ago) and a fairly low value, we just got liability insurance so unless I can get Audi to do the repairs free for a know defect, we are out more than we paid for the car to do the suggested repair. Has anyone out there found success in getting Audi to fix the damages caused by this known defect?
While I was driving one day, I felt something drip down my leg. Upon closer inspection, it was a stream of water coming out of the lower left section of the dashboard right next to a bunch of wires. It had been raining quite a bit. I took it into the dealership and they identified the problem, a clogged sun roof drain. First, that is a huge design flaw. Why would you route backed-up water to just above the dash with no exit route except into the dash? Makes no sense at all. Second, if Audi knows that's a frequent problem, and I don't know why they wouldn't, why isn't drain inspection/clearing included as routine maintenance and especially when it can cause some major electrical damage when it does happen? The dealership is trying to tell me it won't be an issue, which doesn't seem to be the case after reading all of these comments.
I Have water leaking into my 2002 Audi A4 Quattro 1.8T on the driver side only. My Wiring on that side was fried as a result and caused me to have to replace the wiring from the ECM under the floor to the Main box in the engine compartment. When we poured water onto the windshield,we seen where the leak is coming in from. The plastic box that the PCM sits in isn't sealed and has a gapping hole. To fix the water from leaking in,you must remove the whole box from the car and put a rubber silicone seal to keep the water from draining into the interior.Then place the whole box back into place. The whole set up for this area is just garbage. Hope this helps
water leaks into the cabin and causes the transmission to "clunk" when placed into reverse.
notce water on passenger side of vehicle, so said to myself I must myself I forgot to close passenger
window and a week latr afte heavy rain I notice about an inch of water on passenger rear floor board
and now I can"nt reset airbag light and no seatbelt warning or doors open messge
Same problem - clogged plenum tray. Interior electrical systems went haywire - no interior lights, trunk won't open, zero power in windows/stuck open. My 7 yr old daughter was frightened to put it mildly!!! Went to Audi dealership and they quoted $14,000 to fix. Yes 14k. This is insane- going to post on social media - a problem these cars have had for years and they want to charge me 14 grand.
I own 2007 Audi A4 Cabriolet. On a day trip, right after a major rain storm here in CA (first in a long time), I started getting ear-splitting alarm from back of the car. Lasted 15 seconds... stopped... came back intermittently. By the time i started my return trip that day, the alarm was coming more frequently, my electronic door and trunk locks were no longer working, windows wouldn't roll down, my glove compartment lock was chattering like it was haunted, and i was getting false alarms about hood being open. Close to getting home, i lost my panel lights and my headlights temporarily.

Went to dealer next day. Turns out plenum tray drains had been blocked by leaves and debris. Water from the storm had backed up and gotten into the car and trashed the convenience module under drivers side seat, thus all the lock problems. The floorboards on both sides had gotten wet too. I had noticed that but thought it was from our wet feet after skiing that day.

The dealer told me to not bother fixing the car! That I could expect to have electrical trouble from here on, nothing they could do to guarantee getting all the water out etc. And that it would cost $4000 to have carpet replaced on top of $1400 it cost (parts plus labor) to get the convenience module replaced and that given the mileage on the car and future maintenance i'd likely have to do, not worth it to sink more money in. I was dumbstruck.

A friend who owns Audis heard about this and told me that Audi actually had a class action lawsuit back in 2009 on this problem as a design problem, but I researched that and found out the suit stopped short of calling out my model year. Clearly though it's still happening because others past 2006 have reported it. I did more research and found out that Audi had updated their Scheduled Maintenance checklists in 2010 to add "checking and clearing plenum tray of leaves and debris" to the 35,000 and 75,000 service checklists. My dealer had done ALL of my service! Yet clearly they had not done this check; I looked back at all my maintenance records and it wasn't even on their list. I had gotten my 75,000 mile service from them a year ago. I was about to go ballistic on my dealer with this evidence and demand they pay for everything when another friend pointed out that my insurance might cover it.

Yes, they did. In the end, they covered the module replacement, plus removing and drying all the carpet and padding, disinfecting everything just in case (against mold or mildew), and checking and lubricating the electrical system contacts. All together the module replacement and car stuff cost $4000, of which I had to only pay my $500 deductible. I still may try to get that back from Audi. (However, I learned along the way that if my insurance company had deemed this problem to be a result of "negligent service", they could have refused to cover it and I'd have been totally screwed. Thank goodness they honored the claim.

Hope this helps someone else. If you live in a place where it rains less frequently, be sure to get your plenum tray or "cowl drain" area checked before any storms. It's not something you can easily get to yourself without removing some stuff in the back of the engine compartment near windshield.
I had this problem a few months ago after I left my car in the garage for a few months. Had to replace it.
Driver side floor completely swamped. Then water started dripping from the roof in the back, flowing over my amplifier and satnav near the left rear pillar.
Had the tubes flushed and refitted - one actually had gotten loose!

Now there is a constant cracking sound coming from the speakers even with the amp removed (hopefully that thing is ok).

Now after the cleaning i STILL had water coming down into the cabin to the left and i discovered the isolation foam behind the dashboard ( a little part is visible with opened drivers door) was completely soaking wet.

Will need to figure out where this comes from and how this can be fixed but it looks like water is still not getting out correctly.
water leak behind driver seat, caused an electrical problem with my car. it is not an inexpensive problem. I took it to audi and this is what they told me. There are three moduals that control the electricity in my car, the convience modual (is the one that has been damaged and allows me to roll down the windows and sunroof and pop the trunk and gas cap and turns on the interior lights of the car)...all of which i cannot use now due to this interior water damage that has caused this expensive problem. its about 1300 to replace the modual.
when RAINS all electric system gets crazy and this happens:
interior lights are flushing
Exterior lights does not turn off
alarm sound any time for not reason
emergency light flash all the time
windows do not work
some times car does not start, so I disconnect battery for a minute, reconnect it again, and car turn on
The starter sytem strats the car sometimes and does not start at times. It does not start when it is cold
In the last few days when I leave for work in the morning the brakes are as hard as a roc,they will not go down at all so needless to say the brakes do not work when they do that but after awhile it will go back to normal,very frustrating and scary.