Hello there,
as you can see from the topic subject, the check engine light came on. I went to a service and the fault code was P0234 - Turbocharger/Supercharger Overboost Condition. The guy erased the fault code and checked how is the turbo performing. And he said everything seems to be normal, it wasn't overboosting at that time at all. After that, I drove for a few hundred kms and it came back. :-/ As I didn't have time to go back to the service I was just driving, suddenly it just went away.
However, a friend of mine loaned me a OBD2 connecter so I can perform the diagnostic myself, and even though the check light wasn't on the dashboard the software still found the same fault code - P0234. After erasing it for a second time and coming back for a third time I decide to ask for an advice in here. :-/
However, I have not noticed any change in power performace, it is the same as it used to be. Though, the fuel consumption increased with about half of litre per 100kms, but I am not sure if this is just not because of the cold weather recently.