Seat Exeo Automatic Transmission Shifting Problem

I also own an Exeo, and I experienced similar automatic transmission problems not long ago. The transmission indicator light illuminated, and the shifting became quite unpredictable, almost like a slipping transmission. Have you checked your battery and overall electrical system? It might sound unrelated, but undervoltage can cause havoc with the electronic control units (ECUs) that manage the automatic transmission.

That's interesting. I hadn't considered a voltage issue. When you say undervoltage, do you mean a completely dead battery, or could it be something less obvious? I'm not very experienced with car electrics. Did you also experience the emergency mode?

It wasn't a dead battery, but rather a fluctuating voltage due to a failing component. The emergency mode was definitely present, limiting the gears available. If the voltage drops too low, the transmission control unit can misinterpret signals and cause erratic shifting, basically a slipping transmission. A transmission flush might help temporarily, but if undervoltage is the root cause, the problem will return. I would recommend having a workshop check the electrical system before assuming it's purely a transmission issue or degraded transmission oil.

I appreciate the shared experience. It appears that the undervoltage situation was indeed the culprit. The mechanic identified a faulty voltage regulator, which was causing the erratic transmission behavior. After replacement and a transmission flush, which cost 240€, the Seat Exeo shifts smoothly again. Thank you for your assistance.