One problem related to adaptive equipment has been reported for the 2006 Audi S4. The most recently reported issues are listed below.
I own a 2006 Audi S4 with bi=xenon hid lights. Numerous amounts of times the indication comes up that I have a dipped headlight. This in turn is because the headlight is off and I'm driving at night. This safety violation will end up costing me every time I go to the dealership to get new parts installed and labor and the high probability of a ticket for having a head light out from the police or other agencies in the area.