Mini Countryman Hybrid Engine Running Lean

Reduced engine power, a check engine light, rough running, and jerking – those are definitely symptoms that need attention. Lean running conditions in a hybrid Mini Countryman can stem from several things. First, have you checked the mass air flow sensor? A faulty MAF sensor can cause the engine control unit (ECU) to miscalculate the air-fuel mixture. Also, when was the last time you inspected or replaced your spark plugs? Finally, are there any unusual smells, like gasoline, coming from the exhaust or around the intake manifold?

Thank you for your response. I have not checked the mass air flow sensor, and I am not familiar with how to do this. Could you explain where it is located and how I might test it? Also, the spark plugs were replaced approximately 30000 km ago. I do not smell any gasoline.

Given the symptoms and mileage, a faulty fuel injector is a strong possibility. The mass air flow (MAF) sensor is typically located in the intake ducting after the air filter. Visually inspect it for debris, but be careful not to damage the delicate wire inside. Cleaning it requires a special MAF cleaner. However, if the problem persists and you're not smelling fuel, it's best to have a professional diagnose the fuel injectors. A diagnostic scan can pinpoint which injector is malfunctioning, and they can perform tests to confirm. Running lean for an extended period can damage the catalytic converter, so prompt action is advisable.

I appreciate your expertise. I took the Mini Countryman to a workshop, and they confirmed the fuel injector on cylinder one was faulty. The total repair cost, including parts and labor, was 515€. The car is running smoothly now.