S60 passenger seat electrical fault

I had a similar issue with the power seats in my S60. The error message was the same if I recall correctly. Have you checked the seat wiring harness under the seat? Sometimes a loose connection can cause this, especially if the battery is weak or failing.

Thanks for the tip! I haven't checked the wiring harness yet. Where exactly should I be looking for loose connections? Is there a specific connector that's known to cause problems?

Yes, the main connector block under the seat is a common culprit for the S60. However, given that your garage suspects the battery, I'd recommend addressing that first, as a low voltage condition can certainly trigger spurious errors and affect the seat motor. If the problem persists after replacing the battery, then it's time to investigate the wiring. If you are not sure what to do next, visit a workshop to get it checked out to avoid further problems.

It was indeed the battery combined with a faulty seat motor. Replacing both fixed the issue. The whole repair came to 290€. Thanks for pointing me in the right direction!