What can cause my check engine light to come on? on 1999 Audi A4 Quattro

What can cause my check engine light to come on?

1 answer
The check engine light indicates that the computer has detected a malfunction in the engine/emission control system and has diagnostic codes and data stored which would be essential in diagnosing the problem.
A technician with a scanner could access the diagnostic codes and data and then be able to give you a diagnosis.
If you want to find a specialist, here's a directory link for you:
https://repairpal.com/directory?address=30236&car_brand_names=Audi