Koleos exhaust back pressure sensor issue

I own a Koleos too, and your issue sounds eerily familiar! I had similar symptoms - warning light and poor engine performance. I didn't notice the smoke though. Do you have any error codes? Might help to pinpoint the exact issue. Have you tried resetting the ECU?

I haven't tried resetting the ECU, as I am not too familiar with that. I am a total novice when it comes to car repairs, and I prefer to leave such things to professionals. However, I am trying to get a rough idea of what is broken, so I can't get ripped off at the repair shop. Was it actually the exhaust back pressure sensor in your case?

Yup, it was indeed the exhaust back pressure sensor! Replacing it solved all the problems. I'd suggest taking it to a trusted mechanic for a proper diagnosis and repair. Don't risk driving it too much further, because you could damage the car, and that is going to be a lot more expensive.

I took your advice, and it turned out to be the exhaust back pressure sensor! The workshop charged me 245€, but at least it's fixed now. No more smoke and the warning light is gone. Thanks again for sharing your experience!