S40 Terminal 30 Electrical Error

I'm having a weird electrical issue with my 2012 Volvo S40 diesel. I'm getting a 'Terminal 30 continuous plus interrupted' error. The car struggles to start, especially in the cold. I've checked the usual suspects – fuses seem okay. Could it be the starter motor on its way out, or perhaps a bad earth somewhere?

4 comment(s)

Terminal 30 issue on a Volvo S40? That's power supply related. Have you load-tested the battery? A heavily discharged or defective battery can cause all sorts of spurious errors. Rule that out first before chasing more complex electrical gremlins. What's the mileage?

Mileage is at 149353 km. I haven't load tested it specifically, but the voltage seems normal. Could it still be the battery even with a decent voltage reading? Is there any way to confirm if the battery is heavily discharged?

Yes, voltage alone isn't a reliable indicator of battery health, especially under load. A load test will show its capacity. However, given the symptoms and the error code, combined with that mileage, I'd strongly suspect a battery issue. Consider taking it to a workshop; they can diagnose it properly.

Thanks for the advice! I took it to a shop as suggested and you were spot on - the battery was heavily discharged and defective. New battery installed and the problem is resolved. Repair cost 290€

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