Seat Arona Diesel Engine Trouble

Rough running and check engine lights are never good signs. The fact that the error memory stores something is helpful though. Did you notice any changes in fuel economy recently, or any unusual smells? Have you checked the airflow sensors? Sometimes a faulty reading there can throw the whole system off. It might be worth checking the basics before assuming the worst, although with that mileage, injector issues aren't unheard of. Onboard diagnostics can be a bit cryptic, so let's try to eliminate simpler causes first.

Thanks for the quick reply! I did not check the airflow sensors. Where exactly are those located, and how could I check them? As for the fuel economy, yes, I think it has become worse over the last weeks. But I wasn't sure if it was only my impression.

Okay, the worsening fuel economy is a strong indicator. While checking airflow sensors can sometimes reveal an issue, the error code pointing to quantity drift compensation is quite specific to the fuel injection system. Given the symptoms and the error code, especially with that mileage, it's increasingly likely you're right about the injector issue. A system reset might temporarily mask the problem, but it won't fix a failing injector. My advice would be to take it to a workshop with experience in diesel engines and fuel injection systems. They can properly diagnose which injector is failing and perform the necessary tests. Sorry it couldn’t be a simpler fix!

Thanks a lot for your help and advice. It was indeed a defective injector. The garage reset the quantity drift compensation after replacing the injector, and the engine is running smoothly again. The error is gone. The fuel economy seems to be back to normal. It cost me around 515€ in the end.