Vectra Rear Window Heating Issue

I had a similar issue with my Vectra, though your symptoms sound more pronounced. Does the light on the switch illuminate when you try to activate the rear defroster? It could be a relay, or even a blown fuse. Have you checked those?

Yeah, the light comes on, so I figured it wasn't the fuse. A relay, eh? Whereabouts is that located, and is it something I can easily swap out myself, or am I looking at a proper garage job? I'm no mechanic, but I can handle basic stuff.

Given the light is on, it probably rules out the fuse and the switch. While a relay is possible, the error code and both heating circuits being affected points to a more general power supply issue to the heating system. In my case, it turned out to be a heavily discharged/defective battery causing voltage drops that affected the heating circuits. The error memory was also showing unrelated errors, probably from the same voltage issue. I would strongly recommend taking it to a workshop with diagnostic equipment to properly assess the electrical system. They can pinpoint the fault accurately.

Took it to the shop, and you were spot on – battery was on its way out. Voltage drop was messing everything up. New battery and they cleared the error, total cost 290€. Rear window and windscreen heating are both working perfectly now. Appreciate the help!