Peugeot 107 start stop issue

Sounds plausible. Start-stop systems are very sensitive to battery voltage. A heavily discharged or defective battery can definitely cause those issues. Has the car been struggling to start lately? Maybe get the battery tested?

The car starts normally, so I didn't suspect the battery. But what do you mean by 'heavily discharged'? Does that just mean it's old?

Not necessarily just old. It could be that it's not holding its charge properly anymore, even if it can still start the engine. Modern cars draw power even when they're off. I'd still recommend getting it checked, because if it's not the battery, then the problem could be somewhere else in the start-stop system, and that is difficult to pinpoint. I’d go to the workshop.

Okay, thanks for the advice. I took it to a workshop, and you were right – the battery was the culprit. Cost me 290€ to replace, but the start-stop is now working again.