Seat Ibiza auxiliary heater problem

Based on the error stored in the memory and the inability to activate the parking heater, a defective glow plug is a plausible cause. However, it is also worth inspecting the auxiliary heater's coolant lines for any signs of a coolant leak. A drop in coolant pressure can also prevent the heater from activating. Furthermore, assess the climate control module for any related error codes that might provide additional insight. I had a similar issue on a different vehicle where a faulty temperature sensor was preventing the heating system from operating correctly.

Thank you for your response. Regarding the coolant leak, where specifically should I be looking for potential issues? I am not very familiar with the auxiliary heater's location or the coolant lines involved. Could a problem with the heater core also cause similar symptoms?

Concerning the coolant leak, inspect the hoses connected directly to the auxiliary heater unit, typically located near the front wheel well or under the vehicle. Look for any signs of wetness, staining, or corrosion. A heater core issue is less likely to prevent the parking heater from activating, but it could contribute to general climate control problems. Given the stored error code and the symptoms, I still suspect the glow plug. It is recommended to take the vehicle to a qualified workshop for a proper diagnosis and repair.

I appreciate your detailed explanation and confirmation. I took the Seat Ibiza to a workshop, and they confirmed the defective glow plug in the auxiliary heater. The total repair cost was indeed around 440€. Thank you for your help.