Mini Roadster Overvoltage Errors

Overvoltage issues in modern cars can be tricky. The Mini Roadster's car electronics are quite sensitive. First, confirm the battery's age and condition. A weak or failing battery can cause all sorts of electrical gremlins, including overvoltage errors, due to the alternator working overtime to compensate. Have you checked the voltage regulator on the alternator itself? A faulty regulator can cause power surge, leading to the symptoms you described. What fault codes are you seeing specifically?

Thanks for the quick reply! The battery is about 4 years old, so it might be nearing the end of its life. I haven't checked the voltage regulator directly. How would I go about checking that, and what kind of readings should I be looking for? The fault codes are all over the place, mostly related to sensors and modules reporting high voltage or signal failure.

Given the age of the car battery and the widespread nature of the electrical faults, a defective battery is indeed the most probable cause. Trying to diagnose the voltage regulator directly requires specialized equipment and knowledge. Because you mentioned that the battery is weak and you're seeing a lot of voltage related errors, I'd advise getting the car battery professionally tested or replaced first. If the issue persists after replacing the battery, then you should consider further diagnosis of the alternator failure. Better take it to a workshop to avoid further damage to the car electronics.

Just wanted to close the loop on this. You were spot on! Turns out the battery was indeed heavily discharged. I replaced it, and that seems to have fixed everything. The car runs smoothly again and all the error messages are gone. The new car battery plus diagnostic at the workshop cost me 290€. Thanks a lot for your help!