BMW air flow sensor

Mass Air Flow Sensor Mass air flow sensors are tasked with measuring the amount of air entering the engine via the intake. This mass air flow sensor is known as a hot film sensor which will suffer performance deterioration over time. The sensor is designed to be self cleaning. A faulty or non functioning mass air flow sensor will cause a check engine light and in some cases cause a limp mode. The best way to diagnose a faulty mass air flow sensor is to disconnect it and see if engine idle or performance improves. Mass Air Flow Sensor Failure Symptoms Check engine light illumniated with OBD codes related to MAF sensor faults Engine has rough idle and/or stalls Short term fuel trim is rich at idle or lean under load Constantly runs rich or lean