Audi A6 avant 2006 - Water in passenger footwell - Martin504

Leaves blocked plenum chamber drain and water ingress caused £1300 damage to a ECU (I think!) under passenger footwell. Now no MMI functions working at all. I've never been notified of a known problem by Lancaster Audi, where I bought the car from new. Last service was September 2009 and not yet due for next service. They say that they have no responsibilty for this damage as I've had the car serviced the last 2 occasions at an independant Audi garage. They have inspected the car and agree the damage is as a result of a blocked plenum drain, but that this is due to poor service. My argument is that they can have no idea when the leaves started to block the drain as there is such a long time between services. I also feel this is an inherent design fault.

Has anyone had any success in getting help with this problem? There has been an American class action regarding this and VAG agreed to settle the case. Is there a UK case going on? Any advice would be appreciated!

Audi A6 avant 2006 - Water in passenger footwell - Collos25

This is a common problem on a lot of cars some just get wet carpets others have more serious outcomes such as yours I myself try and keep the plenium chambers and exits clear having once nearly having a disaster with a Rover 75.I don't think you have much chance with the franchised dealer but the garage who serviced the vehicle should carry a small amount of the blame and you the other part I am sorry to say.If I were you I would source an ecu and have it fitted by an independant auto electricians a least that way it should not cost anything like the quote from Audi.

Edited by Andy Bairsto on 18/02/2011 at 09:31

Audi A6 avant 2006 - Water in passenger footwell - 659FBE

This is an absolutely standard design fault on this chassis which VAG have done nothing about. It also affects VW and Skoda clones.

Typically, rather than recalling the vehicles and correcting the fault, VAG have covered their tracks by putting "inspect plenum chamber drains" in the service schedule. So, if this has not been done, you have no redress.

There is in fact a VW branded TSB detailing the fix for this problem, which is to remove the self-blocking bungs and replace the useless open-cell foam seal on the pollen filter housing with a bead of mastic strip. I have done this job on my Superb and the original seal is not fit for purpose.

I think you may have to bear the cost of this dreadful piece of design - which also makes the car dangerous due to rusting of the servo housing - but make sure you get the cause rectified properly. No action from VOSA, despite a car of this weight being unstoppable without a servo.

The VW TSB is 443/06 and the mastic strip needed is AKD 497 010 04R 10. Best of luck - put your energy into fixing it rather than arguing with VAG who have been there a thousand times. Then vote with your cheque book.


Audi A6 avant 2006 - Water in passenger footwell - Peter D

I have just finished cleaning the bungs out on an A6. It is surprising how little debris it takes to bung them up. I regularly check my A6 by flooding the windscreen for 30 seconds with a hose pipe and checking for the two steams of water from under car.

The bungs a 'Platter-pus Bill' type to allow water out but not let engine fumes into the Plenum Chamber. Some owners that have removed the bungs have complained of engine fumes in the car as the plenum chamber hosts the pollen filter thus the source of air for the A/C. Regards Peter

Audi A6 avant 2006 - Water in passenger footwell - 659FBE

If you end up with engine fumes in the plenum chamber after bung removal - you have a problem. Some of the petrol engined B5.5 variants have crankcase breather pipes in that area which are prone to leakage. Other makes of cars manage with holes in the plenum base you could put several fingers through - they don't get blocked either.

I think the animal is a Platypus. My platypus had a cruciform bill which is perfectly designed for the job of getting blocked. Given the safety critical necessity of keeping water out of there, I would remove all bungs (there's one under the servo with a pipe running through it) without hesitation. These cars should have been recalled for this as effective brake failure and engine damage can result.

It's also essential to change the foam seal (which will be split and sodden with water) for a strip of 10mm mastic asap.

How do VAG have the affrontery to sell vehicles in this build state for the sake of 10 ps worth of sealing strip?


Audi A6 avant 2006 - Water in passenger footwell - Peter D

Yes I agree, smelling engine fumes tells you something is not quite right. Removing the bungs also leads to speed related whistling noises. Yep you are right the bungs are better described as Duck Bill's. I have a Passat coming in tomorrow for the same problem. Regards Peter

Audi A6 avant 2006 - Water in passenger footwell - lankem
Had exactly the same problem with water build up in the rear passenger footwell. I have a 04 Audi A6 - checking through previous comments I realised that the water was coming through the ventiilation unit. Recently we had quite alot of rain so I open the bonnet and removed the plastic cover just below the wipers. The area under the cover was full of water. I cleaned the drains at either side of the kwindscreen - these were full of leaves. Then if you get a metal coat hanger or a welding rod and prod the rod around a third of the way across from the passengers side you will come across a drain hole. My blockage was dead leaves - once cleared the water came gushing out !
I'm now in the process of drying out they car with blowers as some of the eclectics have failed - going to make sure the car is now bone dry..
Audi A6 avant 2006 - Water in passenger footwell - dieselnut

Iankem, you mention the plenum drains but not the pollen filter housing.

You need to remove this housing & discard the original foam seal, then either get the replacement seal from VW as highlighted by 659, or fill the recess with a mastic or silicon sealant & make sure it is proud of the recess. Clean the area the filter housing sits on carefully as it will be full of crud, before refitting.

The carpet & thick foam underlay really need to be removed from the front passenger area to dry it properly. I did this by removing the passenger seat (don't switch on the ignition while it is removed or you will have the Airbag light come on, which can only be reset by the dealer or VAGCOM) & cutting the carpet accross to the centre console. Dry out the CCU ECU & associated plugs, check inside the CCU for water. Dry out the plugs & check for corrosion, some wires may break off if it has been wet for some time. Also check the near side off the footwell wall where there is a lot of wiring & more connectors.

Audi A6 avant 2006 - Water in passenger footwell - bomber0405
Hi, I need help with this issue. I've got a 2005 A6 C6 saloon and I have water in the passenger footwell, found this morning. I thought a window had been left open but when I got to work I noticed water leaking down the right hand side of the footwell and after readin the forums it seems it is coming from the sill inside the engine.

I read a lot of posts about removing the battery but this is in the boot?!? What needs to be done to get to resolve the problem. Where are the plugs and how do I get to them.

Any help would be appreciated.

Thanks, Ben.


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