Seat Altea Smoke and Warning Light Issue

Sounds familiar. I had a similar issue with my Altea. Have you done any vehicle diagnostics to confirm the exhaust sensor is faulty? What does the engine performance look like?

Yes, I did a scan and it points to the exhaust back pressure sensor. Engine performance is definitely down, and I'm getting smoke when accelerating. Is that what you experienced?

Yep, those were the exact symptoms I had: reduced engine performance and the smoke. It's likely the exhaust sensor. I'd recommend getting it checked at a workshop to be sure.

The exhaust back pressure sensor was the problem. The workshop replaced it for 245€. The warning light is off, the smoke is gone, and the DPF is regenerating again.