Mercedes B Klasse Hybrid Electric Seat Issue

I had a similar issue with my B Klasse. The power seats draw a fair bit of current. Have you checked the battery's resting voltage? A weak battery can cause electrical issues. Is the seat completely dead, or does it try to move and then stop? It could also be a faulty seat module or a wiring harness problem.

Thanks! I haven't checked the resting voltage myself, but the shop mentioned it. The passenger seat is completely dead. Where is the seat module located? I might check it with a multimeter before paying for the repair.

If the seat's completely unresponsive, a dead battery is even more suspect. The seat module is usually under the seat. You'll probably have to remove the seat to get access. Disconnect the battery first! Given the shop suspects the battery and you're getting a dead seat, I'd get the battery professionally tested. It could save you diagnostic hassle. The error stored in the memory is a solid lead.

You were spot on. It was a heavily discharged battery causing the electric seat to fail. They replaced the battery, cleared the error memory, and the passenger seat is now working perfectly. Total cost was 290€ as quoted. Thanks for your input, it really helped me narrow down the problem.