BMW 13627567451 Mass Air Flow Sensor

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The hot film mass air flow sensor sends a varying voltage (approximately 0.5 - 4.5 vdc) to the ECM, representing the measured intake air, with the air mass input signal produced using an electrically heated metal film in the air flow stream. The DME main relay provides the operating voltage to the air flow sensor, and as air flows through, the film is cooled, requiring additional current to maintain a constant temperature, which forms the basis for the input signal. In the absence of an output signal from the air flow sensor, the ECM relies on throttle position and engine rpm inputs to operate the engine, while a faulty sensor triggers the MIL. Common issues with a faulty air flow sensor include difficulty restarting when the engine is hot, stalling after starting, and running only with the accelerator pedal depressed. To address this, switch the ignition OFF and remove the key, then work at the left front of the engine compartment at the air filter housing by detaching the mass air flow sensor electrical connector, loosening the air duct clamp, releasing clips from the air filter housing, and removing the MAF sensor. If the air flow sensor is to be reused, visually inspect it for damage, missing parts, or blockages, and check the intake ducts for cracks and vacuum leaks. Installation follows the reverse order of removal, and for ease, lubricate the large rubber O-ring seal in the air filter housing with assembly lubricant, ensuring all hoses and seals are properly seated. Finally, check for DTCs and clear and reset the ECM memory.

Remove the mass air flow sensor.

The Valvetronic system adjusts intake valve opening and lift based on engine speed and load, with faults detected by the Valvetronic control module and communicated to the ECM for diagnostics.