I have a 2006 A6 3.2 Quattro with 92,000 miles. Absolutely love this car (or so I thought), and really want to get this fixed. I’ve experienced the notorious problems with water getting into the car, and now my MMI is completely dysfunctional (will not turn on, screen is completely blank).

This is my wife’s car. Last week she came home and said she could hear what sounded like water sloshing around inside the car and she also said her stereo would no longer work. I got in the car and heard and experienced the same thing. After some Internet research I’ve learned of all the similar problems with water flooding the car primarily due to clogged drains in the plenum/bulkhead area.

The water had completely saturated the driver’s side (U.S. car, so left side) floor and rear passenger (driver’s side) floor. I pulled up the carpet and was disgusted when I found a few inches of water. I suctioned it all out with a big syringe (about 2 gallons of water), and dried it out for two days with a fan and in a heated garage.

(Picture of the drivers side floor plan after I drained all the water. ECU was dried out as well)


The ECU was sitting in water and I took that out of the black box and put it near a heater vent for a day and dried it out as best as I could. I’ve put everything back together and the car runs fine (it ran fine even when you could hear the water), but the issue is the MMI. I read horror stories about water getting on the Passenger side and affecting the Transmission Control Unit. I have not yet pulled up the carpet on the passenger side, but there is no evidence of any water on that side of car (totally dry). I’m still concerned that I don’t have the actual source of the water leak solved. All the videos and everything I read, show the main culprit being a drain under the battery box. My battery is in the trunk so that does not apply. I removed the bulkhead area cover and even removed my windshield wipers and the cowl at the bottom of the windshield. I vacuumed out and blew out with compressed air all the small leaves and debris that I could get to in the whole area. I could not find any clogged drains as seem so obvious for other older Audi’s.

My main question at this point, is how to troubleshoot the MMI issue. My first thought was that it shorted out a fuse but I can’t find a fuse that directly controls the MMI (I checked a few that seemed related, and all were good).
I did a hard “restart” on it (holding down the three buttons at same time), and that did nothing.

Is there another control box other than the ECU sitting in the floor somewhere that controls the MMI? Is there a way to troubleshoot if it is the MMI control unit (basically all the buttons and controls in the center console), or is it the actual display? I get no lights or power indicator on any of the buttons.

Does the ECU control the MMI, and do I have to replace the ECU?

A few months ago I bought a cheap Vag-com cable and small cd off eBay . I could never get the software to install properly (tried on multiple laptops, and also downloaded it with same failed results) so I’ve not been able to scan for any codes, but if that is my only logical next step, I’ll invest in the right hardware/software to do it, but just need a little direction on how to properly troubleshoot.

Thanks in advance for any help.

 

On my 2002 audi a6 4.2 I had the same problem.

Both my CCM and TCM were soaked, dried them out. And then everything was fine.

My leak was from underneath the battery tray and the ECU container next to the battery and brake fluid. Under the battery there are two drain holes that can easily get clogged up, the water then fills the tray eventually leaking into the car into the passenger and drivers side foot area.

After about a year my transmission went into limp mode so I pulled it out and it was corroded completely. I just replaced it with a matching part number and everything has worked great since.

On my car the Comfort control module is under the drivers foot and the Transmission control module is under the passengers sides feet. I only pulled the lower door trim off to get to both locations though.