S40 Electrical Software Bug

Whoa, that sounds rough! I've got an S40 too, though I'm running the gasoline engine. I had a similar crazy electrical gremlin thing happening last year. My dash was lighting up like a Christmas tree, and the radio would randomly cut out. Did your mechanic mention anything specific about which control unit is throwing codes?

Thanks! The diagnostic report just says 'control unit programming implausible'. Do you remember how your issue was fixed, like which control unit was reprogrammed or replaced?

Ugh, 'implausible' – that's mechanic speak for 'we have no clue'. Honestly, mine was a pain to diagnose and fix. I ended up taking it to a specialist shop. They hooked it up to some fancy diagnostic equipment and eventually traced it to a corrupted software module. They reflashed the ECU and everything went back to normal, but I think you should consult the dealership or an authorized garage, too.

Thanks for sharing your experience! Given the complexities, I agree that getting professional help from an authorized workshop is the best idea.