So I have checked the archives and see multiple theories on this. I just purchased my '04 A4 which only came with one key. I have found a duplicate on ebay with the FCC and part numbers matching my key. The dealers I have spoken to about reprogramming the transponders have given me conflicting reports as to the abilityof a usedkey to take a new code. Some say it's no problem, and some say that the transponder in the key may not take another code if it's already been programmed for another car. Some have also said that both the key that I have and the key that I will buy must be programmed with the vehicle to a completely new code which would suggest that the transponder in the key can be reprogrammedsince the key I have must be reprogrammed, too. Anyway, can any of you sort this out for me, or have any of you bought a used key and had it either work or not work when it comes to transponder coding? Thanks a lot!

Cheers.