Clogged drains can allow rainwater to accumulate in the plenum tray (at the base of the windshield). The water may leak into the vehicle's interior, brake booster, or electrical components, which can lead to major problems. Our technicians recommend keeping the tray clear of leaves, pine needles, and other debris.Google+
Car Problem Reports
Audi A8 Rainwater May Accumulate in Plenum Tray Due to Clogged Drains
Audi A8 Problem
Model Year Affected: 1998
Visitor, 1998 Audi A8, 115,000 mi
Clogged drain caused water ingress into transmission ECU (needing to be replaced)Engine ECU (hopefully still OK) & footwell. I understand the drain points are in the front footwell side walls under the carpet. I have yet to look for these since the car is having the transmission ECU replaced!