Seat Inca Automatic Transmission Issue

That sounds suspiciously like the issue I had with my Inca a while back. Same symptoms: check engine light, the transmission light, and that horrible slipping feeling. Does it feel almost like an engine surge when it happens? The lock-up clutch in the auto transmission was the culprit for me. Have you checked the error codes?

An engine surge is a good way to describe it, yes. How did you confirm it was the lock-up clutch specifically? Was it obvious when the mechanic inspected it?

Well, the error codes pointed to the transmission, and the symptoms matched. Think of the torque converter lock-up clutch like a clutch in a manual car – when it goes bad, you get slipping. It wasn't visually obvious without taking things apart, but a transmission specialist should be able to diagnose it properly. Best bet is to get it to a reputable workshop for a thorough check.

Thank you for your input. I took it to a workshop, and after diagnosis, it appears you were spot on. The automatic transmission converter is indeed defective. Unfortunately, the repair cost is estimated at 2120€. I have approved the repair.