How to troubleshoot a check engine light in a BWM?

I recently noticed that my check engine light has turned on in my BWM. What could be causing this and how can I troubleshoot it myself?

The first thing you should do is check your gas cap. A loose or damaged gas cap can trigger the check engine light. Make sure it is securely tightened.

If the gas cap is not the issue, it could be a problem with your oxygen sensor. This can be diagnosed and repaired by a mechanic.

Another possibility is a malfunctioning catalytic converter. This should also be inspected and repaired by a professional.