Peugeot 807 Battery Sensor Issue

Sounds familiar! I have an 807 too, and I had similar symptoms a while back. Weak starts and flickering lights. Have you checked the battery voltage while the car is running? Mine was all over the place, which pointed to a battery issue. Did you measure any unusual values in particular?

Yeah, I did check the voltage while it was running. At idle, it seemed okay, around 14V, but as soon as I turned on the headlights or the air conditioning, it would dip and fluctuate between 12V and 15V erratically. You mentioned a battery issue – was it the sensor itself that was faulty?

In my case, it turned out to be the battery sensor indeed. I tried cleaning the contacts, but that didn't help. Honestly, with those kinds of fluctuations, you're probably better off taking it to a workshop. They can diagnose it properly and replace the sensor if needed. It's a pain, but better than getting stranded.

Thanks a lot for the advice! I took it to my local shop, and they confirmed it was the battery sensor. Replaced it, and the problem is solved, 315€ including labor. Now the voltage is stable, and the flickering is gone. Really appreciate your help!