Your mass air flow sensor reads the amount of air entering your engine. This information is used by your car's ECM to determine fuel trim and other necessary metrics in order to deliver the best performance and economy. This particular mass air flow sensor is known as a "hot film" type sensor or HFM. The HFM measures the air mass in the air intake. The sensor element consists of a heated sensor over which the intake air flows. The more air is flowing over the membrane, the higher the temperature difference between both measuring areas is rising. As this sensor ages it becomes inaccurate or simply burns out. When this happens your engine may not run properly and you will likely have a check engine light.