Seat Leon Hybrid High Voltage System Error

High-voltage system errors can be tricky. A heavily discharged or defective battery could definitely be the culprit, especially with that mileage. Have you checked for any obvious signs of battery drain, like lights left on or aftermarket accessories drawing power when the car is off? Any recent work done on the electrical system?

No lights left on or aftermarket stuff. But how would I check the battery properly? Is there a specific voltage I should be looking for?

Yeah, it's difficult to diagnose without proper equipment. You'd need to check the voltage under load, which isn't something easily done safely on a high-voltage system. Given the symptoms and error message, plus the fact you aren't seeing anything obvious, an electrical fault is likely the cause for the system malfunction. I'd recommend taking it to a workshop that specializes in hybrid vehicles. They'll be able to pinpoint the issue and repair the electrical wiring if needed.

Thanks, I appreciate it. Turns out it was a defective component within the high-voltage system, causing a battery drain. The electrical wiring was fine, thankfully. The workshop replaced it, and I'm back on the road. Cost me 290€.