Fiorino Rear Window Heating

That sounds frustrating. I had a similar issue with my old Renault Clio. The rear window demister just wouldn't activate. Have you checked the fuses related to the rear window heating circuit? Also, did you measure the battery voltage recently? What voltage does it show when the engine is off and when it's running?

Thanks for the suggestions about the fuses and battery voltage. Which specific fuses are you referring to? What's an acceptable range for the battery voltage both when the engine is off and when it is running?

With my Clio, the fuse diagram was in the manual, and there was one specifically labelled 'rear window heater'. Yours should have something similar. As for voltage, with the engine off, it should be around 12.6V fully charged. When running, it should jump to 13.7-14.7V as the alternator charges it. If it's significantly lower, especially when running, the battery might be the issue. But honestly, with an error code showing, it's probably best to get it checked out at a workshop. They can properly diagnose it. Cheaper than randomly replacing parts!

I appreciate the explanation about the fuses and battery voltage. Given the error code, I agree that a workshop visit is best. The technician confirmed that the battery was defective, causing the rear window heating to fail. The repair cost was 290€.