Master Active Air Flap Fault

Active air flap faults can be tricky. A similar issue caused problems on my old van. Does the engine overheat quickly, or only after a certain amount of driving? Are the air flaps visibly stuck? Check the wiring to the electromechanism controlling the flaps. A loose or corroded connection could easily throw an error code and cause them to malfunction. What's the mileage on your Master? That might give us a clue.

The engine tends to overheat after about 30 minutes of driving, especially at higher speeds. I haven't been able to visually inspect the air flaps yet, but I will check the wiring. The mileage is currently at 172487 km. Could the electromechanism itself be the problem?

With 172487 km, it's possible the electromechanism is failing. Based on your description, it sounds like the flaps might be stuck closed, restricting airflow and causing the overheating. I would recommend getting it checked by a professional, as a defective electromechanism can lead to more serious engine damage. A workshop should be able to confirm the fault and provide a proper replacement.

I took it to a local workshop and, as suspected, the electromechanism was defective. The total repair cost, including parts and labor, came to 590€. The issue is now resolved. Thanks for pointing me in the right direction!