Matrix Rear Window Heating Issue

Sounds frustrating! I had a similar problem with my old Saab 9-5, though the symptoms were slightly different. The error code was vague, and the rear defrost was completely dead. Have you checked the battery's health? A heavily discharged or defective battery can cause all sorts of weird electrical gremlins, like a short circuit. It's like trying to run your house on a dying flashlight battery – things just don't work right. What's the voltage looking like when the car is off and when it's running?

Interesting, I hadn't considered the battery. I'll check the voltage like you suggested. But if the battery is the problem, wouldn't I be having other issues too, like difficulty starting the car? Is there anything else I should test before assuming it's the battery?

Good question. You might expect starting issues, but modern cars are weirdly resilient sometimes. The battery might have enough juice to start the engine, but not enough to properly power high-drain systems like the rear defroster. Think of it like trying to fill a swimming pool with a garden hose – it'll eventually fill, but it'll take forever. Honestly, based on your description and the error code, it's worth getting the battery professionally tested. Could also be a faulty relay or wiring, but those are harder to diagnose without the right tools. If you do not have the proper tools, take it to a workshop.

Thanks for the insights! You were spot on. I got the battery tested, and it turned out it was heavily discharged and defective. Replaced it and the rear window heating is working perfectly now. The bill came to 290€, but it's worth it to have a clear rear window again!