Volvo S60 weak battery and flickering lights

That does sound like it could be battery-related. I had a similar issue with my old Opel Astra. Weak starts and flickering lights are classic symptoms. Have you tried testing the battery's voltage? Do you have a multimeter available to check it?

Thanks for the insight. I don't have a multimeter, unfortunately. Is there a way to be 100% sure it's the battery sensor before I consider replacing it? It seems like a costly part to change on a whim.

I understand your concern about the cost. Without proper testing, it's difficult to be absolutely certain. Given the symptoms, it's likely the battery sensor. If you don't have the tools to test it yourself, perhaps taking it to a workshop for a diagnostic check would be a wise move. At least then you'll know for sure before committing to the repair.

Thanks again for the advice. I took it to a workshop, and you were right – it was the battery sensor. The total repair cost was 315€. The car starts perfectly now, and the lights are stable.