Vauxhall Vectra Undervoltage Errors

Wow, that sounds frustrating! I had similar issues with my old Peugeot 307 a few years back. My car would struggle to start, and the dashboard would light up like a Christmas tree with error messages. Did you check the battery voltage? Is it within the normal range when the engine is off and when it's running?

Yeah, I did a quick check with my multimeter. It seemed low, but nothing crazy low. Could it be the alternator not charging the battery properly? What was the cause in your case with the Peugeot?

Turns out, it was a faulty alternator. The Peugeot dealership ran a diagnostic and confirmed the charging system wasn't working correctly, so the battery wasn't getting charged while driving. I would suggest getting a proper diagnostic check. That way, you know for sure before throwing parts at it. It could save you a lot of time and money!

I appreciate the advice. I took it to a local mechanic, and after a thorough check, it turned out to be exactly what you said: a defective battery. They replaced it, and the car is running perfectly now! Total cost was 290€. That's what I call a happy ending!