SpaceTourer rear window heating issue

It sounds like an electrical issue, especially with both the front and rear defrosters acting up. Have you had any battery issues lately? A heavily discharged or defective battery can cause all sorts of weird electrical problems in modern cars. I saw something similar with a Peugeot 5008 once.

That's interesting. The battery did seem a little weak the last time I started it. Could that really stop the rear window heating from working, even with the engine running?

Yes, definitely. Modern vehicles are very sensitive to voltage drops. The body control module might disable non-essential functions like rear window heating to conserve power if it detects low voltage. I think you need to get your battery tested, it's very likely the root of the problem. Then erase the error memory. If the problem isn't resolved, you need to visit a workshop.

Thank you for the helpful advice. As suspected, the battery was the issue. Replacing it and erasing the error memory solved the problem. The bill was 290€ Much appreciated.