Seat Mii rough running engine

I am familiar with the Seat Mii, although I do not own the 2020 model specifically, I have experience with similar models. The symptoms you describe, particularly the rough engine running and check engine light, are indeed indicative of potential combustion misfires. Has there been any recent work done on the engine, such as spark plug replacement? What is the state of the air filter? Are there any unusual smells emanating from the exhaust?

Thanks for getting back to me. Spark plugs haven't been changed recently, and the air filter seems okay, visually anyway. No weird smells either. Could it really be the fuel injector like I suspect? And if so, is that a big job to fix?

The symptoms you describe strongly correlate with a defective fuel injector. While a visual inspection of the air filter is a preliminary step, it may not reveal underlying issues. Given the mileage and the symptoms, a malfunctioning injector is a plausible diagnosis. Replacement typically involves removing the intake manifold for access, disconnecting the fuel lines and electrical connections, and installing a new, properly calibrated injector. It is advisable to consult a qualified technician for proper diagnosis and repair. Attempting such a repair without the necessary tools and expertise can lead to further complications.

Just wanted to say thanks for the advice. Took it to a workshop, and they confirmed it was a faulty injector. Got it replaced, plus they did a full diagnostic. Cost me 515€, but the car is running smoothly again. No more engine misfiring or jerking!