Skoda Praktik auxiliary heater problem

I had a similar issue with my Praktik's auxiliary heater. Check for coolant leaks around the heating system. A drop in coolant level can prevent the heater from firing up. Is the blower motor functioning correctly? A faulty blower can also trigger a fault.

Coolant level seems stable, no visible leaks. The blower motor is working fine, pushing air when the regular car heater is on. You mentioned a coolant leak preventing the heater from starting. Is there a specific sensor or component that detects low coolant for the auxiliary heater?

Yes, there is a coolant sensor integrated into the auxiliary heater system. However, since you've ruled out a coolant leak and the blower motor is operational, a defective glow plug is the most probable cause, as you suspected. I'd recommend getting it checked at a workshop. It's often difficult to access the heater and replace the plug without proper tools.

Fault code indicated the glow plug. After replacing it, the auxiliary heater is working. The total cost was 440€ including labor.