Ccrosser Auxiliary Heater Failure

Auxiliary heater issues can be tricky. When you say 'cannot be activated', does it attempt to start at all, or is it completely unresponsive? What's the exact error code stored? These heaters sometimes have safety mechanisms that prevent them from firing up if, say, the coolant level is low, or if the blower motor is malfunctioning. Is it a factory-installed heater, or an aftermarket one?

The heater remains completely unresponsive, no attempt to start. I don't have the precise code, but it refers to a general malfunction. The heater is factory-installed. How do I check the coolant level and blower motor?

If it's completely unresponsive, and especially with a general malfunction code, it sounds like an internal fault. Coolant level is easy - just check the reservoir. The blower motor is related because some systems won’t allow the heater to run if the blower isn't working to prevent overheating inside the heater unit itself. However, given the lack of any start attempt, a defective glow plug is a very likely culprit. Considering it's a factory system and the age of the vehicle, it really points towards needing professional diagnosis. I'd recommend a workshop visit; they'll have the proper diagnostic tools.

Understood. I will schedule an appointment with a workshop. The issue was a defective glow plug. Repair cost was 440€.