V40 Auxiliary Heater Issue

Based on the symptoms and error code, a defective glow plug within the auxiliary heater unit is a likely culprit. Have you noticed any unusual smells or sounds coming from the ventilation system when attempting to use the heater? It would also be useful to check the temperature sensor readings to see if they are within the expected range.

Thanks for the quick reply! No unusual smells or sounds, thankfully. Where exactly is the temperature sensor located? Is it something I can easily check myself, or am I better off just taking it to a workshop?

Given the complexity of the auxiliary heater system and the potential for further complications, I would advise against attempting a repair yourself, especially without specialized tools and diagnostic equipment. Continuing to run the heater with a defective glow plug can cause additional damage. I recommend taking your Volvo to a qualified workshop for diagnosis and repair.

Okay, appreciate the advice. I was hoping to avoid the workshop, but it sounds like the best course of action. Just got a quote for 440€, glow plug replacement. Thanks again for pointing me in the right direction!