Mercedes EQC Error Messages and Control Unit Issues

These symptoms do suggest a potential issue with the BUS system. Have you checked the battery voltage and ground connections? A weak battery or poor ground can sometimes cause similar erratic behavior in electronic systems. If the voltage and grounds are solid, a faulty cable connection is plausible. You might want to gently inspect the connectors for any signs of corrosion or damage.

Thank you for the quick reply. Regarding your suggestions, how would I go about testing the ground connections properly? I have a multimeter available, but I am unsure of the correct procedure to follow to ensure an accurate test.

Testing ground connections involves checking the voltage drop between the battery's negative terminal and various ground points on the vehicle's chassis and engine. Ideally, the voltage drop should be minimal, close to zero. However, with your reported symptoms and stored error codes indicating a BUS system issue, it would be prudent to have a qualified technician diagnose the problem. A defective cable connection to the control unit is likely, and could be resolved for around 155€, but it requires professional intervention.

I appreciate the advice. It seems the issue is beyond my current capabilities. I will schedule an appointment with a qualified technician to inspect the cable connections, as you suggested. Thank you for confirming my suspicions and providing an estimated repair cost. I will add to this thread once the issue is resolved.