How to troubleshoot a faulty tail light on an Audi A3?

My Audi A3's tail light is not working properly. I've checked the bulb and it seems fine. How can I diagnose and fix the issue?

First, check the fuse for the tail lights. If it's blown, replace it and see if the problem is resolved. If not, then it could be an issue with the wiring. Check for any loose connections or damaged wiring. It's also possible that the tail light circuit board is faulty and needs to be replaced.