One problem related to power assist brake has been reported for the 2000 Audi A4. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2000 Audi A4 based on all problems reported for the 2000 A4.
Brakes power assist fail at / just after startup when selecting reverse or drive while the air conditioning is on. I reported the problem to the Audi exchange in highland park, IL last year. They were unable to reproduce the problem, at the time as I was unaware that it only occurred when the a/c was on and at low speed after initial start up. This occurred again this summer when I was trying to move out of a parking spot and was unable to stop. The result was that I hit another car at low speed causing no damage to either.