I've noticed water collecting in the spare wheel well of my 2004 S4 Avant over the last few months, causing heaving condensation, so I've been trying to work out where it's coming from. I've ruled out the washer system: I didn't use the rear washer for over a week and inside the tailgate trim is dry (where the pump is as well as the upper tailgate section) but the water still accumulated.
I pulled all the trim out of the floor and it looked like water was getting past the rubber seal on the bottom left-hand side (red ring in photo) and I could see the path of travel along the body (1), under the main floor plastic, soaking the felt triangle underneath* (2), down the body into the well (3) and collecting at the bottom (the 3 pads are also soaking*).
*Soaking fabric could have been condensation rather than water passing through it directly.
I bought a new boot seal from Audi for about £60 but that hasn't fixed it (although the seal must be better as the tailgate needs a little extra force to close now). Looking at today's photo the evidence of ingress in the red ring is still present too.
I've uploaded a few more photos taken today of the tailgate area. I was hoping someone could let me know if there's any trim/sealing parts missing. Most the wet parts of the tailgate area are just where I opened it at lunchtime after this morning's rain but you can see water on the trim of the tailgate where it seems to be coming in.
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