Fuel Flap Stuck Closed

I had something similar on my R Klasse, though it wasn't exactly the same. Is the car throwing any error codes? Mine turned out to be an electrical fault with the lock actuator for the fuel filler. Check if other functions are also acting up. Could be the same thing.

Electrical fault, huh? The error memory does have something stored, and yeah, some other stuff isn't working right either. Where exactly is this lock actuator? Is it easy to get to?

Okay, if other functions are affected and there's an error stored, it does sound like an electrical problem potentially affecting the fuel flap lock actuator. I wouldn't advise trying to get to it yourself unless you're experienced. You could make things worse. I'd suggest taking it to a workshop to get it properly diagnosed. Could save you money in the long run. If it is what I think it is, and the linkage isn't just defective, you'll need someone to sort it.

Thanks for the advice! Took it to a workshop like you said. Turns out it was the lock actuator. Cost me 210€ but at least the fuel flap works again! And the other issues are gone too.