Mini Clubman running rough mixture preparation error

Reduced engine power, stalling, and a check engine light? Sounds frustrating! Have you checked for any obvious vacuum leaks, particularly around the intake manifold? A rich mixture could also point to a faulty oxygen sensor. Is the catalytic converter still original?

Vacuum leaks around the intake manifold, I can check that. But how would a bad oxygen sensor cause a rich mixture? And how do I know if the catalytic converter is bad? Never messed with that before.

A faulty oxygen sensor can definitely mess with your fuel/air mixture. It provides feedback to the engine control unit, and if it's sending incorrect data, it can cause the engine to run rich. As for the catalytic converter, a blocked or damaged one can also affect engine performance, but usually you'd get other symptoms too. Given the symptoms and the error code, a defective fuel injector is definitely a strong possibility. Maybe consider taking it to a professional, it sounds like it might require some specialized tools.

Just wanted to give an update. Took my Clubman to the shop, and you were spot on! Turns out the fuel injector on cylinder one was completely shot. New injector, and it's running like a champ again. Cost me 515€ all in. Thanks again for the help, really appreciate it!