An MAF, or Mass Air Flow, sensor is a device used to measure the density of air flowing into the engine. The MAF sensor can go bad for numerous reasons, resulting in symptoms a car operator can use to help determine and resolve the problem.
A lit "Check Engine" light is an early symptom of an MAF sensor going bad. The MAF sensor measures the air and fuel mixture that is sent to the engine. Once the air/fuel mixture ratio is off to a certain degree, the car computer activates the engine light. An incorrect air/fuel mixture also results in other MAF failure symptoms, such as lower gas mileage, poor engine performance, stalling, knocking and shuddering.
The MAF sensor is subject to harsh environmental factors, such as heat, cold and vibrations, all of which can damage the sensor element. Gas fumes, vehicle backfiring and water condensation can also settle on an MAF sensor and cause it to go bad.
A car's computer can be analysed to help diagnose an MAF sensor. An auto mechanic can analyse a car computer, or the car operator can perform a diagnosis with a digital auto diagnosis sensor, which is available at most auto repair stores.