The hot film mass air flow meter is an electronic air flow sensor which measures air flow; the mass of air which is flowing through the car's engine, and is an important part of the Engine Control Unit (ECU). The hot film mass air flow meter has an important part to play in the performance, power and efficiency of the car's engine.
The hot film mass air flow meter is usually found in the plastic housing between the engine and the air filter. It's attached to the air hose at one end and the air filter box at the other. The engine needs the correct amount of air and fuel flowing through it in order for the fuel to burn in the cylinders and for the engine to ignite or spark at the right time. If the ignition sparks at the wrong time, there will be less power in the engine and it will try to make up for this by using more fuel, significantly reducing fuel efficiency, which in turn increases the car's CO2 emissions.
The hot film mass air flow meter works by measuring the air flow and sending these measurements to the car's ECU which, based on these measurements, will control the amount of fuel flowing into the engine at the point at which the ignition sparks.
The hot film mass air flow meter will, with continued use, wear out or stop working. When this happens, the performance of the engine is likely to be affected and engine emissions will be higher. A fault in the hot film mass air flow meter will cause the Check Engine light to show on the dashboard to indicate a problem with the hot film mass air flow meter. A broken hot film mass air flow meter can sometimes prevent a car from idling properly (the ability for a car's engine to run while it's not moving) and may cause the engine to splutter and stall. If there's a fault in the hot air mass air flow meter a replacement hot air flow mass meter is the perfect replacement part.