Dreaded A5 Coupe Leak :( - HEEEELP!

Hi all,


I’ve got the dreaded water leak that’s filling up the rear side compartment (where the amp sits). Luckily, the car is parked nose-up, so the water has been draining toward the back rather than forward into the cabin.


Here’s what I’ve found and done so far:


The leak appears to be coming through the body panel itself, which is both strange and concerning. Water is seeping through a small gap in the panel. When I pour water through the boot drain channels, it runs down over the black tail light gutter/funnel area — and sometimes over the tail light itself. When that happens, I can see water starting to seep through.


My only thought at the moment is that the seam on the body panel may have failed.


So far I have:

 

• Removed the rear bumper and sealed the pressure vents
• Replaced the main boot seal, as the old one was in poor condition
• Applied sealant from the inside of the panel (currently curing, so I’m waiting to see if that resolves it)

However, I have a feeling the bumper may need to come off again and something sealed externally — I just can’t pinpoint exactly where the water is getting in. I've attached a viideo below and despite it looking like there is a pinhole, there isn't it was just black dirt


I’ve been chasing this issue for a while now, so any advice or suggestions would be greatly appreciated.


Thanks in advance.