Peugeot 206 Auxiliary Heater Fault

That sounds frustrating! I had a similar problem with my old Opel Astra. The symptoms were identical – parking heater refusing to start and an error code popping up. In my case, it turned out to be a faulty glow plug. It's like a tiny light bulb that helps ignite the fuel in the auxiliary heater. Have you checked yours?

Interesting! I haven't checked the glow plug specifically. Where is it located, and is it difficult to access? Is there any specific test I could perform to confirm it's defective?

On my Astra, it was tucked away near the heater unit itself, but the 206 might be different. Honestly, unless you're very comfortable with car electrics, it's probably best to have a workshop take a look. They have the diagnostic tools to pinpoint the issue precisely. While it could be something else, glow plug is a really strong candidate, given your symptoms and the error code. I'd prepare for around 440€ if it is that.

Thanks so much for the advice! I took it to a shop, and you were spot on – it was indeed the glow plug. Appreciate the help!