I had to put a new battery in my 2001 A4 1.8T quattro. I knew the radio would show "safe" when I powered it up after replacing the battery. I have the code and the procedure for unlocking the radio. The procedure did not work.

I called the Audi dealer where I bought the car and their response was "sometimes the software gets screwed up when you disconnect the battery". My only option they said was to buy a new radio. Great option!!!!

Does anyone have any experience with this problem???