Saxo diesel generator issue

I also own a Saxo, and those symptoms sound very familiar! Weak lights and starting issues definitely point towards an alternator problem. Have you checked the battery voltage when the engine is running? It should be around 14V. If it's significantly lower, then the alternator isn't charging the battery properly.

Thanks for the quick reply! I haven't checked the voltage myself yet. I am not sure where to measure it. Could you please provide more details about the location and how to measure it with a multimeter?

Checking the voltage requires know-how, so it's best to get it done by a professional. Given all the symptoms, it really does sound like a faulty alternator. I'd recommend taking it to a workshop to confirm and get a quote for a replacement. It's not worth risking further damage by trying to fix it yourself without proper experience.

Thank you for your help and advice. I took the car to a workshop, and it turned out to be a defective generator, just as we suspected. The repair cost was 960€. It's now fixed and working perfectly again.