One of the key components of your vehicle’s electronic fuel injection system is the mass air flow sensor, or MAF. Sitting between the air filter and the intake manifold, the mass air flow sensor measures the amount of air entering the engine.
In modern automobiles, an intake air temperature sensor is already built into the MAF. Modern vehicles also use hot-wire type mass air flow sensors, which have a small, electrically heated wire. A temperature sensor measures the air temperature near this wire.
Surprisingly, it takes only a tiny electric current to do its job. Even an engine that’s merely idling will still keep the wire hot enough for the sensor to detect the airflow around it.
Naturally, opening the throttle allows more air to flow over the hot wire, cooling it down as the air passes over. More and more electrical current is needed to keep the wire hot as more air flows in, keeping the electrical current proportional to the airflow.
The engine computer receives the data when the chip installed inside the MAF translates the current into a digital signal. The computer uses this digital signal to calculate how much fuel needs to be injected to keep the air/fuel ratio balanced. It also uses these readings to determine the shift points in a vehicle’s automatic transmission.
As you can see, this component does a lot of things and failure can be a safety hazard. Here are the symptoms of a failing mass air flow sensor.
1. The Check Engine Light Comes On
Many things can cause the engine light to come on, so this one symptom doesn’t necessarily mean the MAF is the culprit. However, it’s still one of the signs of a failing air flow sensor. Even a sensor that doesn’t need replacing can trigger this warning light.
Whenever this light comes on, it’s best that you bring your car or truck to a mechanic to be looked at. Sometimes the problem isn’t catastrophic, but so many things can trigger this light that it’s better to be safe than sorry.
2. A Misfiring Engine or Rough Running Engine
If your engine is misfiring or just not running smoothly, it can point to an imbalance in the air/fuel ratio. If this is occurring due to a failing sensor component, it’s because the computer isn’t getting the right data and doesn’t know how much fuel the engine needs.
3. Problems Starting the Engine
Several problems can cause the engine to refuse to turn over, so drivers shouldn’t jump to the conclusion that the problem lies with the MAF. However, a vehicle that struggles to turn over, misfires, and runs roughly is pointing to a problem with the air/fuel ratio. The car or truck should be brought to a mechanic as problems will continue to mount until the sensor is repaired or replaced.
4. Black Smoke Coming from the Exhaust
This is more of an emergency situation that requires the attention of a mechanic ASAP. When black smoke is pouring out of the exhaust, the air mass in the engine intake is imbalanced to the point of being dangerous.
What to Do if You Suspect a Failing Mass Air Flow Sensor
The best thing to do is to bring your vehicle to a mechanic. The only way to conclusive diagnose a problem with the MAF is by using a sensor, which your mechanic will have. You don’t want to risk further damage to the engine or the safety of yourself or your family by allowing the problem to continue.