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Megane Engine Running Rich

My 2023 Renault Megane with a gasoline engine is running excessively rich at 49196 km. I've noticed reduced engine power, the check engine light is on, the engine idles roughly, fuel consumption is up, and acceleration is jerky. I suspect the injection valve or injector system. The air filter is clean, and I don't see any vacuum leaks. Has anyone else had these issues? Any ideas?

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I had similar issues with my 2018 Opel Insignia: rough idling and reduced power. It turned out to be a faulty mass airflow sensor. Have you checked that? Even though you suspect the injectors, a bad MAF sensor can mess with the air-fuel mixture and cause a rich condition. Do you have the error code?

Thanks! The error code is P0172, 'System Too Rich (Bank 1)'. How did you diagnose the faulty MAF sensor on your Insignia? What readings or tests did you do?

I monitored the MAF sensor's output with an OBD-II scanner while the engine was running. The readings were all over the place, even at steady speeds. Since you have the P0172 code and suspect the injectors, I'd suggest a mechanic do a thorough check. Measure the fuel pressure and check the injector spray pattern.

I took it to a workshop, and it turned out one of the fuel injectors was defective, causing the rich running. They replaced the injector, and the engine runs great now. The total cost was 515€ Thanks for the help!

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