Arkana Engine Running Rich

I had a similar issue with my BMW 3 Series diesel – reduced power, check engine light, rough running. It was a combination of things. I initially suspected the MAF sensor, but that wasn't it. Did you inspect your air filter or catalytic converter? They could cause a rich running condition if clogged.

Thanks, I checked the air filter, and it's fine. I haven't checked the catalytic converter. Could a clogged catalytic converter cause the engine to run rich? What's the mechanism? I was focused on the fuel injectors. Do you remember the error code for the check engine light?

A partially clogged catalytic converter can increase backpressure, interfering with exhaust expulsion and leading to a higher concentration of unburnt fuel, mimicking a rich condition. My error code was P0172, indicating a rich fuel mixture. Fuel injectors are a valid concern, but get the catalytic converter professionally inspected and get a diagnostic scan to check the error code. With several symptoms, I'd suggest a workshop visit.

Thanks for the catalytic converter and error code advice. I took the car to a workshop. The injectors were defective. The repair, including replacement, cost 515€.