Audi 100 C4: Water in A-Pillar - Fix It!

Hi,
"Water is leaking into my Audi 100 C4 from the A-pillar, specifically from a foam plug through which the cables to the driver's door pass. Of course, that plug can't be sealed properly. The question is, where does water most commonly enter the A-pillar on this model? The car does NOT have a sunroof or anything similar."
Christian.

How about the coolant reservoir (located under the windshield, behind the engine)?
Are all the processes free?

Yes, if they are on, it's coming from the heating system.
I might have found the cause, but I need to observe it further to be sure.
A seal on a weld seam in the water reservoir, located between the fuse/relay box and the support bracket, had ruptured. I have resealed it and am waiting to see if the problem is resolved.

Yes, I'm curious to see what happens.

Hi,
The error has not occurred again. I wasn't entirely sure at first, but it seems there might have been some residual water leaking out.

Great, so you've finally found it.