AIR-MASS SENSOR

The air-mass sensor, typically located after the air-filter, determines the amount of intake air for an exact definition of the load in the combustion chamber under varying ambient conditions. It uses a heated sensor film or diaphragm over which the aspirated air flows. The diaphragm’s temperature profile is taken by temperature sensors at two fields of the diaphragm. The stronger the air-flow, the higher the temperature difference between the measuring fields. From this difference, an integrated electronics module in the HFM calculates the air-flow and feeds it to the engine control unit as digital signals. Bosch offers the Hot Film Mass (HFM) air-flow sensor, also called Manifold Air-flow Sensor.