SupraIV electric seat malfunction

I had a similar problem with my SupraIV. Have you checked the seat wiring harness and connectors for corrosion or damage? A bad connection in the power seat circuit could cause those symptoms.

I did a quick look at the accessible wiring, but I didn't use a multimeter to check continuity and voltage. Where did you see the most likely spots for failure on yours?

Mine was a corroded connector in the seat control module under the seat cushion. Without a full diagnostic, it's hard to say for sure. The electric seat system is complex, so a qualified tech might be best. I think I can confirm your suspicion.

I took it to a certified technician as you suggested. The problem was related to the discharged battery. They replaced the battery, cleared the error, and the repair cost 290€.