Clogged sunroof drains can allow water to enter the interior and accumulate under the carpet where various control modules are mounted. Over time, the accumulated moisture can damage the control modules.Google+
Car Problem Reports
Audi A6 Quattro Water From Clogged Sun Roof Drains May Damage Control Modules
Audi A6 Quattro Problem
Average Mileage: 102,675 mi (95,000 mi - 115,000 mi)
Visitor, 2000 Audi A6 Quattro, 95,000 mi
2000 Audi A6 Quattro - After a heavy rain storm, I found about 1/2 inch of water in the rear passenger side foot well. After researching the issue and reading numerous reports of the same problem....it makes me wonder why Audi has not addressed this design flaw. This is my first Audi and its probably my last.
The drain under the hood was clogged with leaves. Reached into the pit of water, removed leaves, water drained. NOw to fix the water damage inside the car - mechanic removed entire interior and dried the carpet in heated garage for 10 days. The whole carpet has a 2 inch foam underside that acts like a sponge. Must be removed and dried or you will get never ending mildew and mold. He also removed the computers and detailed those with metal cleaner. Eventually made it run at 100%, without replacing anything. You need to get the water out before it damages the computers under the carpet!!!!!!!!!
Visitor, 2000 Audi A6 Quattro, 99,000 mi
Entire Floor is flooding when it rains