How to troubleshoot a check engine light in my Audi A3?

My check engine light suddenly came on in my Audi A3 and I'm not sure what to do. How can I troubleshoot the issue and find a solution?

First, check the gas cap to make sure it's not loose or damaged. If that's not the issue, you can use a OBDII scanner to retrieve the error code and diagnose the problem. Alternatively, you can take it to a mechanic who specializes in Audi for a professional diagnosis.