C5 Overvoltage Errors

My 2004 Citroen C5, gasoline engine, is throwing overvoltage errors. Mileage is 72971 km. The ECU logs multiple overvoltage faults and various systems are failing. Battery seems weak on startup, and things are electrically unstable. I suspect a dead cell or a short. Has anyone seen this before?

4 comment(s)

I had similar issues with my C5. Lots of weird electrical problems and overvoltage warnings, plus the battery kept dying. Check your alternator's voltage regulator; it's a common culprit. When the voltage regulator fails in the alternator, it can cause overvoltage, and damage sensitive electrical components.

Thanks for the tip! Do you recall what symptoms you had exactly? Was it a difficult fix, or did you end up having to go to a workshop to replace the alternator?

Yeah, the symptoms were pretty much the same: fault codes, weird system failures, and a flat battery. I tried a few things, but eventually, I had to take it to a workshop. Replacing the voltage regulator didn't solve the issue; the entire alternator was faulty. Best to get it professionally diagnosed.

You were spot on! Workshop confirmed it. The battery was heavily discharged and defective, causing the overvoltage. A new battery fixed everything! Repair cost me 290€ Thanks for pointing me in the right direction!

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