Skoda Yeti rough running diagnosis

Sounds suspiciously like a fuel injector problem. I had similar symptoms on my Yeti. Has the 'check engine' light illuminated? When these gasoline engines misfire, it can damage the catalytic converter. Do you smell gasoline in the oil? Do you have access to VCDS to check the error codes? It is like a clogged artery restricting blood flow to your engine. These new gasoline formulations are not helping.

You mention checking the error codes. Which ones specifically indicated a problem? And did you also experience increased fuel consumption?

The error codes pointed to a misfire on cylinder 3, which initially led me down the path of spark plugs and coil packs. Eventually, it was diagnosed as a faulty injector. Yes, my fuel consumption went up noticeably before the engine started running really rough. If it is indeed the injector, I suggest getting it sorted quickly. Raw gasoline washing down the cylinder walls is never a good thing. Best to take it to a competent workshop.

The workshop confirmed a faulty injection nozzle. Replacing it made the engine run smoothly again. It cost 515€. Hopefully, the emissions will be back to normal now.