Mini Countryman rough running issue

Rough engine running on your Mini Countryman? Check engine light on... sounds like you're on the right track thinking about the fuel injection. First things first, have you checked the airflow sensors? A faulty sensor can mess with the fuel/air mixture and cause similar symptoms. Also, what's your fuel economy like? Has it gotten worse recently? Have you tried any fuel additives to clean the injectors? A simple reset procedure for the ECU might help temporarily, but it's probably a band-aid if an injector is actually defective. I would scan the error memory before proceeding.

Thanks for the quick reply. Where exactly are the airflow sensors located, and is there a way to test them without special tools? Is there a specific reset procedure for the ECU you suggest?

Okay, so the 'reset quantity drift compensation' error code pretty much confirms it's fuel injection related. As for the airflow sensors, they are located in the intake, directly after the air filter box. You'd ideally test them with a multimeter, but without tools, visually inspect them for any obvious damage or debris. As for the reset procedure, disconnecting the battery for about 30 minutes sometimes works, but honestly, with that error code, that sounds like a hardware issue. It looks like an injection valve/injector is defective. I'd suggest getting it to a workshop before you do much driving.

Update on my Countryman. Took it to my trusted mechanic. They ran some onboard diagnostics and confirmed it was the reset quantity drift compensation related to a faulty injector, just like you suspected. Ended up costing me 515€, but she's running smooth as butter now. Thanks for the help!