1. It is compatible with Citroen cars including: C1,C2,C3,C4,C6,C8,C-CROSSER,NEMO,BERLINGO,JUMPY,JUMPER,AX,SAXO,BX and so on. But please pay attention, according to our customer's experience, this item can not works good at C5 new models. 2. It is compatible with most Peugeot cars from 1995 If you have the two types of cars, please pay attention, please check with us first before purchase. 3. Diagnostics is performed via OBD-II connector (which is located near steering wheel) or via manufacturer-specific connector (only older cars, pre-2001).