Sprinter Auxiliary Heater Problem

That sounds familiar. I had a similar problem with my old Volvo, though it was diesel. The parking heater wouldn't work, and it turned out to be the glow plug. It's like a lightbulb filament burning out. Did the error code specifically mention the glow plug? Also, did you check the fuses for the auxiliary heater? Sometimes it's a simple fix like that before replacing parts.

Yes, the error code pointed to the glow plug. I haven't checked the fuses. Where are they located? Are they in the main fuse box under the hood, or somewhere else?

The error code confirms the glow plug issue, which is good. Checking the fuses is still a good idea. The fuse box location varies, but it's likely under the hood or near the driver's side footwell. The owner's manual should have a diagram. At that price, and knowing the error code, I would have the workshop do it. Auxiliary heaters can be hard to work on, especially if they're hard to reach.

I appreciate the advice. I checked the fuses, and they were fine. I took it to the shop, and the glow plug was bad. 440€ later, the parking heater works. Thanks for confirming my suspicions.