Audi 2012 tdi q7 repair

Since the check engine light is on, there are fault codes stored in the cars memory. Scan with an OBDii scanner for the codes. They should be 4 digit codes to help pinpoint the area you need to look. You can do this yourself or a local auto parts store can do it for free. Post the 4 digit codes back here for more help. It's probably related to the gearbox malfunction. I would get it checked out sooner than later before possible damage is done.