: It supports a wide range of older Audi models, including the Audi 80, A3, A4, A6, A8, S3, S4, TT, and Q7.
However, for several reasons:
Matching a new engine control unit to the existing immobilizer.
You cannot simply buy a blank key and cut it to match the lock. The car must be told to "accept" the new key’s transponder. To enter this programming mode, diagnostic tools (VCDS, ODIS, etc.) require a (e.g., 03251 or 20953). Without this PIN, programming a new key is impossible without replacing expensive hardware.