What is the most efficient way to troubleshoot the Audi A3's check engine light?

I recently purchased a used Audi A3 and the check engine light has come on. What steps should I take to diagnose and fix the issue?

First, use an OBD-II scanner to read the specific error code. This will help narrow down the issue and provide guidance for potential fixes. Then, research common issues with the Audi A3 and see if the error code matches any known problems.

If the error code does not point to a specific issue, it's best to take the car to a certified mechanic for a diagnostic test. They will have the necessary tools and knowledge to accurately diagnose the problem and provide an appropriate solution.