I recently replaced my 2.1 WBX with a 2001 ALH TDi engine. With the removal
of the old wire  harness I also pulled out the grommet on the firewall
where the wire harness goes from the ECU to the engine. I installed the new
wire harness and added various additional wires such as the wires to the
solar panels. The new ECU is located where the old one was, underneath the
rear bench. I was not able to reuse the old grommet. Thus the new wires go
now through the fire wall without a grommet and the hole is still partially
open. I am still looking for a good way to close up the opening to prevent
air-, water, mice etc from getting in?  Good suggestions are very
much appreciated? As you all know, the hole is not easily accessible.

Thanks

Bruno