XC40 Overvoltage Errors

That sounds rough! Overvoltage errors across multiple systems points to something bigger than a bad sensor. A weak battery makes me think something is up. First, check the battery terminals and connections to ensure they're clean and tight. Have you recently jump-started the car or had electrical work done? That could cause a surge.

Thanks! I checked the battery terminals, and they seemed okay, although there was some minor corrosion that I cleaned off. No jump-starting or electrical work recently. Could a faulty voltage regulator cause overvoltage issues even with a seemingly okay battery? Or maybe a bad ground somewhere?

A faulty voltage regulator is a prime suspect for overvoltage issues. It should keep the voltage in check. A bad ground could also contribute, but usually that causes undervoltage or erratic behavior. Given the complexity of the XC40's hybrid system and all those error codes, I'd suggest taking it to a qualified mechanic or Volvo dealership. Electrical issues can be a nightmare to track down without the right tools.

Thanks! I suspected it might be beyond me. I'll book it in with a local garage and mention the voltage regulator. They ran a diagnostic and found the car battery was causing the issue, apparently heavily discharged or defective. It cost 290€ to replace the car battery. Fingers crossed it sorts everything out!