Aygo Overvoltage Errors

I'm experiencing a disconcerting issue with my 2006 Toyota Aygo diesel. I'm getting many fault memory entries relating to overvoltage, with subsequent failure of various systems. The car also seems to struggle to start sometimes, like the battery is weak. Mileage is currently at 31909 km. Could it be a power surge? Is this a common issue?

4 comment(s)

I had a similar experience with my old 2012 Renault Megane, although the symptoms were slightly different. It sounds like the voltage regulator in your alternator might be faulty, like a tap that's stuck on full blast, constantly overcharging the system. Have you checked your battery's voltage with a multimeter while the engine is running?

Thanks for the quick reply! I don't have a multimeter, I'm afraid. I'll ask a friend. But if it is the voltage regulator, could the battery issue have caused it? Or is it more likely the regulator failed and then damaged the battery?

It's a bit of a chicken-and-egg scenario, isn't it? In my case with the Megane, the garage suspected the failing regulator had killed the battery. I would recommend getting it checked by a professional with proper diagnostic tools. It's a safety issue, really.

Thank you! I appreciate the advice. It turns out the battery was heavily discharged and defective, causing the overvoltage errors. Replacing it fixed the issue - the total repair cost was 290€. This was a huge help!

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