The 88's and 89's were soft coded, meaning the code could be changed. Originally the code was 1111 on all the radio's. Other than that unless you can contact the previous owner(s) you may have to go to Audi with about $100 and get a rebuilt unit. Good luck DF Dave Flagg Autohaus So Burlington, VT 802-658-2277 www.vtbusiness.net/autohaus/