B Klasse Start Stop Issue Resolved

I had something similar with my B Klasse, though mine isn't a hybrid. The Eco mode and the start-stop system just stopped working. Engine stalling at lights was a real pain. Did you notice if it happened after a lot of short trips? Maybe the battery isn't getting enough charge? I'm just throwing ideas out there. Have you checked the battery voltage?

That's helpful. You mentioned the engine stalling. Did you also get a warning light on the speedometer? And if you remember, what did they say was the issue with your car? It could help me narrow things down.

Yep, definitely had the warning light. Honestly, I'm not completely sure what the underlying cause was back then. The workshop guys mentioned something about a discharged battery affecting the start-stop system's functionality. In your case with the hybrid system it could be more complex. I'd probably take it to a workshop to get it checked properly. It might save you some headaches.

Appreciate the input. Took it to the workshop, and you were right – the auxiliary battery was heavily discharged. Replaced it for 290€ and the Start-stop system is working again. No more engine stalling. Thanks again!