Mass Airflow Sensor
Every time you press down the accelerator or release it, this changes the airflow to the engine, which means less or more fuel needs to be sprayed into the combustion chamber. To keep this under control, your vehicle is equipped with a mass air flow sensor, also known as a MAF sensor, which measures how much air enters the engine when it’s running. Based on this information and the data received from some other sensors, the engine control unit calculates the amount of fuel supplied to the engine.
A MAF sensor is usually housed in the air intake, somewhere between the throttle body and the air filter.
Symptoms caused by a bad MAF sensor
Your check engine light is on
The engine control module monitors most of the vehicle’s sensors. The MAF sensor is no exception. If the control module detects any problem, it will turn on the check engine light.
Reduced performance and poor acceleration
A malfunctioning MAF sensor provides incorrect readings, which often leads to engine stalling and misfiring, resulting in poor performance.
Poor fuel economy and high emissions
A faulty MAF sensor may cause the engine control unit to supply more fuel to the engine than it needs. This will affect your performance and emissions.
Is a MAF sensor repairable?
A MAF sensor should be cleaned before its replacement. You may use one of the dedicated cleaners available on the market. If this will not help, the sensor must be replaced.
MAF sensor maintenance is not a straightforward job, so most of us can tackle it. However, if you feel uncomfortable working on the engine, you may hire a mechanic to do the trick. Besides, you will need a scan tool or code reader to reset the computer and clear out trouble codes.
MAF sensor basics
Not all MAF sensors are the same. There are two main types of MAF sensors, including hot film and hot wire. Both types rely on a heated element placed in the air intake stream. The air that passes through it cools the element, changing the current needed to maintain its temperature. The engine control unit measures this current and, based on it, calculates the airflow.
While most vehicles come with a MAF sensor, some of them utilize a speed density system where the job of a MAF sensor is performed by other engine sensors.
A MAF sensor serves several purposes at the same time, measuring the airflow and its temperature. Although, some vehicles come equipped with an individual intake air temperature sensor for the most accurate temperature readings.
A standard MAF sensor features a three-wire connector. The first wire is for powering and heating the internal element. The second one is used to send signals to the control unit, while the last one simply completes the electrical circuit. On some MAF sensors you may also find the fourth wire if this sensor comes with a built-in intake air temperature sensor.