Peugeot 407 starting issues

I had similar symptoms on my 407. Weak starts and flickering lights usually indicate a problem with the charging system. The battery voltage regulator, often integrated into the alternator, could also be at fault. Have you checked the battery voltage when the engine is running?

I haven't checked the voltage with the engine running. However, when the engine is off, the voltage seems normal, which is why I am focusing on the sensor. Is there a way to confirm whether the battery sensor is defective?

While a normal voltage reading when off might seem reassuring, a faulty sensor can still provide incorrect data to the car's computer, affecting charging. Given the symptoms and diagnostic reading, it is quite probable the sensor is the issue. I suggest visiting a workshop for a definitive diagnosis and repair.

I appreciate your advice. I visited a local workshop, and the diagnosis confirmed a defective battery sensor. The repair cost, including parts and labor, was 315€. The issue is now resolved. Thank you again for your help.