Seat Exeo knocking combustion issue

I also drive a Seat Exeo, and your description sounds eerily familiar to an issue I experienced. Reduced engine power and jerking, especially under acceleration, were my primary symptoms. Did you by any chance check the ignition timing? That, coupled with potential combustion chamber deposits, could be your culprit. It's like trying to run a marathon with clogged arteries.

Interesting. Ignition timing wasn't something I specifically looked at. When you mention combustion chamber deposits, are we talking about carbon buildup on the piston heads themselves? Did you manage to resolve the issue yourself, or did it require professional intervention?

Yes, carbon buildup on the piston heads and cylinder heads was the primary issue. It was causing pre-detonation, throwing off the ignition timing, similar to how a pebble in your shoe throws off your stride. I initially tried fuel additives, but they offered minimal improvement. Ultimately, I had to take it to a workshop for a proper cleaning of the combustion chamber. Considering you are seeing smoke and have errors stored, a professional diagnosis is probably your best bet.

Took the Exeo to a workshop. Diagnosis confirmed combustion chamber deposits causing the detonation. They performed a chemical cleaning of the cylinder heads and replaced the spark plugs, costing 425€. Seems to have resolved the issue. Power is back, no more jerking or smoke. Thanks for the input.