Help Please Water under driver's side carpet, need to remove dash panel!

Hi all,

Apologies if there is already a post on this but everything I find relates to the common issue with the sunroof. Car is an '09 A4 (B8) Avant S-line 2.0 tfsi quattro with NO sunroof.

I've got what is now a slow water leak into the cabin. On a squelchy rear footwell being reported by our 4yo, I initially removed the driver's seat, lifted the carpet to expose a small pond deep enough to just about reach the bottom of the electrical harness housing under the seat. Yep, the one with the airbag connector block. Water is clear, no fragrance to it and occurs when it rains only, so points to rain water ingress imho. After sponging it all out it became evident water was trickling in from in front of the dash somewhere as the sound deadening spongey stuff under carpet and in front of pedals was all sopping wet. So far I have (in chronological order);
  • Cleared scuttle and unblocked drain holes both sides (removed seemingly pointless rubber grommets)
  • Replaced windscreen (by professional fitter) - sound deadening at top of dash was very wet, A pillars dry. This improved but did not eliminate the problem.
  • Got hose on scuttle, water streaming in when over ECU so replaced ECU compartment and lid (rubber seals looked perished)
  • Replaced slightly damaged rain water deflector - clips into bonded trim at bottom of windscreen then connects to scuttle cover.
Water no longer streams in after all the above but after returning a few days of rain later there is a definite very small bit of new wetness collecting and the sound deadening at the bottom behind the pedals releases water when squeezed.

I am at the point where I believe the only way of conclusively investigating further is to remove the dash but I can't find a guide anywhere to do this for the B8. So I'm open to thoughts and if anyone has or can point me to a guide for removing the dash panel? Has anyone without the sunroof had this problem?


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spartacus 68

Registered User
My advice before you start to haul out the dash, is hang fire. I'd be inclined to rule out everything else before you progress to some major work. You will also need a well lit workshop, this isn't the kind of thing you want to be doing on the driveway. Even a domestic garage is tight, just because you have to contort yourself to getting under the dash for clips, etc.

I know water damage is a pain, I'm still chasing a leak on my A4 Allroad panoramic sunroof but refuse to change the cassette which is the only real solution, which will only fail again as the design is fundamentally flawed.

Back to your predicament. There's a dropbox link here on Audizine which relates to a B8. Now apparently there's only 7 bolts, but before you get to that you need to remove the steering wheel, instrument cluster, MMI screen, climate control, centre console, etc.

Refer back to this link. There's a rubber grommet next to the brake servo - that seems to resolve the problem for 'traficant' post 15 onwards. This is on an A6, but worth checking to see if it's on A4. I'm sure it's an access grommet for additional wiring to engine or fuse box.


Well-Known Member
Gold Supporter
Wouldn’t something like this here help trace the leak? - assuming you’ve not tried before....
Thanks for your inputs! Ok so definitely agree it’s worth ruling everything else out first. [mention]spartacus 68 [/mention] I did see that drop box link, looks intricate and the bits i really need are the chapters that would be hyperlinked in the source (elsawin?).

I’ve had a look at the grommet by the servo before, it’s in good nick and is positioned so far over above the bellhousing there would be wet in other places if it was defective. However I’ll replace it too as it might be somehow invisibly deformed and causing some kind of backflow effect then finding a route to under the accelerator pedal.

Thanks for your link to the dye [mention]RAF_S7 [/mention] would be perfect but at the painfully slow rate it seems to be weeping it would take a few hundred gallons before anything becomes apparent to the floorpan under the dash due to the spongey sound deadening it has to soak through first. It may also be too diluted by what it’s already holding. Would be useful for once the dash is out though, will keep it in mind for if it comes to that.

I’m hoping the very slow trickle rate (a drip maybe every 5 mins) is somehow an extraneous effect of my interfering with the residual water gathered at the bottom of the sound deadening when i go in to check each time. It seems to only squeeze out and get damp around it when i get my mitts in there, no puddle is formed over a few days of rain, the floor pan just feels sweaty in places. If this is the case and it is residual from a couple of weeks ago, with any luck the remainder will evaporate off with minimal mould growth now the spring is allegedly on it’s way.

Looks like the best approach is to put it all back together and check again in a couple of months. If by then there is a significant puddle beyond the possible residual weeping then I’ll have to give the dash out a go. Will be flying blind on the chapters not visible in the dropbox doc so if anyone has read this far and has access to the linked pages in that guide I’d be very happy to hear from you, to say the least.

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