BMW 13627593624 Mass Air Flow Sensor

N55 engines utilize a Siemens SIMAF GT2 hot-film air mass meter, which features planar metal resistors on glass, offering high vibration resistance, improved accuracy across all operating temperatures, and reduced sensitivity to air pulsations and moisture. The intake air temperature sensor is integrated into the mass air flow sensor and functions as an NTC thermistor that receives a 5-volt reference current and ground from the ECM. A malfunctioning air flow sensor can lead to issues such as difficulty restarting the engine when hot, the engine starting and then stalling, or the engine only running when the accelerator pedal is depressed.

Switch ignition OFF and remove the key. Working at the left front of the engine compartment at the air filter housing, detach the mass air flow sensor electrical connector, remove fasteners, and take out the mass air flow sensor. Check the intake ducts for cracks and vacuum leaks. The installation is the reverse of removal, and it is important to inspect the O-ring and replace it if necessary. After reinstalling, check for fault codes and reset the ECM memory.

From September 2006 onward, a digital mass air flow sensor is employed, where a duty cycle signal corresponds to changes in intake air mass, eliminating the need for signal conversion in the ECM.