A gas-powered engine depends on a very precise mixture of fuel and air to achieve the ideal combustion conditions, which is why most vehicles are equipped with mass airflow sensors, or MAFs. The MAF is designed to measure and regulate the amount of air entering the engine. If this component begins to fail, it could drastically reduce the quality of the engine's performance.
There are two different types of mass airflow sensors, hot film and hot wire. The difference is the material used to measure the air flow - either a nickel foil grid or a platinum wire. They are both heated electronically to be hotter than the temperature of the incoming air. When the air passes through, it cools the sensor, which causes an increase in electrical current. The amount of electricity needed directly correlates to how much air is passing through the sensor.
The engine control unit relies on information provided by the MAF to determine how much fuel should be injected into the combustion chamber. If the MAF readings are off, the car could wind up using more fuel than necessary. This will not only impact fuel economy, but it could damage the engine. Drivers should be able to recognize the warning signs that may indicate the sensor is beginning to fail, and the part should be replaced as soon as possible when this occurs.
The most common sign the MAF may be failing is the check engine light. If this comes on, the MAF could be the reason, but it may indicate a number of other issues. The car's computer will need to be checked to determine why the light is on. This can be done with a digital auto diagnostics scanner that plugs directly into the vehicle's computer.
When the sensor begins to malfunction, it could cause a slew of engine performance issues. This may include declining fuel economy and engine stalls. The motor may also shake or you might hear knocks or pings coming from under the hood. These issues may arise before the check engine light comes on, but they are also common signs of many other mechanical problems, so it can be difficult to determine whether the MAF is the root of the engine trouble.
Particles can also build up on the sensor. When this occurs, the part does not necessarily need to be replaced. However, it can and should be cleaned to prevent complete failure and improve performance. The MAF can be removed and opened to allow access to the sensor. Use electronics cleaner to clean off the metal wire or foil. Just make sure the sensor is completely dry before replacing it in the car.