99% of air mass (hot film etc.) sensors fail shortly after air filter replacement. It is important to clean air filter housing externally and internally before replacing filter.

Particles of dust or dirt will get imbedded into the film area of the sensor and render sensor inoperative.

In addition, many sensors are replaced for no reason. Often, universal scanners will display air mass sensor fault code when in fact the crankshaft or some other sensor has failed.