How to diagnose a Lin bus?

Hello, unfortunately without the vehicle in front of me and a BMW capable diagnostic tool, I can't possibly guess what steps to take here. There's no "common" issue to share and there's no way of knowing what variables you may be experiencing. I can say this does not seem to be a terribly common issue so a technician working on the vehicle would desire to know if there has been any accidents or physical issues that have occurred with the vehicle. https://repairpal.com/auto-repair-near-me