Two problems related to horn assembly have been reported for the 1999 Audi A6. The most recently reported issues are listed below.
My 1999 Audi A6 avant ignition switch failed causing the lack of turn signals, windshield wipers, heater and horn. The bernardsville Audi dealers claims it "fried some wires" which to me sounds like a safety and fire hazard.
Ignition switch failure we caused the lights, turnsignla, horn, windshield wipers and washers and heat in the car to no work. Very dangerous. This was caused by ignition switch melted wires from the heated steering wheel.