What Is a MAF Sensor (Mass Airflow Sensor)?
The Mass Airflow (MAF) sensor is mounted in the air intake pipe between the air filter and the throttle body. It measures the mass and temperature of air flowing into the engine using a heated wire or film element. This data is sent to the engine management ECU, which uses it to calculate the precise quantity of fuel required for the correct air-fuel ratio. The MAF sensor is one of the most important inputs to modern engine management systems.
What Does the MAF Sensor (Mass Airflow Sensor) Do?
For efficient combustion, a petrol engine requires a stoichiometric air-fuel ratio of approximately 14.7:1 by mass. The MAF sensor is the primary means by which the ECU determines how much air is available for combustion, allowing it to inject the correct quantity of fuel. A malfunctioning MAF sensor causes the ECU to calculate an incorrect fuel quantity, resulting in rich or lean running conditions that affect performance, economy and emissions.
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Get My Free Fault Scan →Symptoms of a Failing MAF Sensor (Mass Airflow Sensor)
MAF sensor faults cause a wide range of symptoms including rough idling, poor acceleration, stalling, black or white exhaust smoke, significantly reduced fuel economy and an engine management light. On modern vehicles the ECU can often detect MAF sensor deviation and enter a limp mode with reduced performance. Cleaning the MAF sensor with specialist MAF cleaner spray resolves the fault in approximately 30 percent of cases.
When Should the MAF Sensor (Mass Airflow Sensor) Be Replaced?
MAF sensors are replaced on failure — there is no preventive replacement interval. Contamination from oil mist (from a faulty crankcase breather) or silicone contamination from non-approved intake sealants are common causes of premature failure. Never clean a MAF sensor with general-purpose electrical contact cleaner — only use a product specifically formulated for MAF sensors.
If you are experiencing symptoms related to your maf sensor (mass airflow sensor) and are unsure whether it needs replacing, a free MotorLoom fault scan can help identify whether the component is likely at fault - giving you the most likely cause and estimated repair cost before you visit a garage.
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Related Parts
Other components that work alongside or are related to the maf sensor (mass airflow sensor):