Mercedes C Klasse fuel flap issue resolved

The symptoms you describe, including the error memory and loss of other vehicle functions, suggest a more comprehensive electrical fault potentially affecting the electric actuator or the lock actuator. Is there any visible damage to the fuel door itself or the surrounding area?

I've inspected the fuel door and surrounding area and found no visible damage. If it is an electrical fault, is there a specific component, such as the electric actuator or the cable release, that commonly fails in these models? Or should I get it checked in a workshop?

Given the lack of visible damage and the involvement of multiple systems, an electrical fault affecting the actuator is probable. You could inspect the wiring harness leading to the fuel door for any obvious breaks. However, diagnosing the precise electrical issue requires specialized tools. Do you have access to such tools? If not, a workshop visit is advisable.

I took your advice and brought the car to a workshop. It turned out to be a faulty lock actuator. The repair, including parts and labor, cost around 210€. The fuel flap release is now working perfectly, and the error is gone. I appreciate your help in pointing me in the right direction.