Mercedes C Klasse auxiliary heater problem

I own a similar Mercedes C Klasse, and I encountered a comparable issue with my auxiliary heater not long ago. Was the error message you received specifically referencing the glow plug, or was it a more generic fault code related to the heating system? Have you noticed any unusual smells or excessive smoke when starting the engine, which might indicate a problem with fuel combustion in the auxiliary heater?

The error code was somewhat vague, something along the lines of 'Auxiliary Heater Malfunction'. No specific mention of the glow plug, that was just my hunch. No weird smells or smoke either. Could a faulty blower motor regulator also cause this? I read somewhere that it could affect the heating system. What was the eventual fix for your issue?

In my case, the error code was similarly ambiguous. I understand your concern regarding the blower motor regulator; however, my experience suggests that a defective glow plug is the more probable cause, particularly given the symptoms you described. Considering the lack of specific error codes and the process of elimination, I recommend consulting a qualified technician for a thorough diagnosis and repair. I ended up paying approximately 440€ for the replacement and labor at the workshop.

I appreciate the insight. Sounds like a trip to the shop is unavoidable. At least now I have a better idea of what to expect. Thanks for sharing your experience!