What is a MAF Sensor? (Mass Air Flow Sensor)
The MAF sensor stands for Mass Air Flow sensor. It measures the amount (mass) of air entering the engine and sends this data to the ECU to calculate the correct fuel injection.
Function of the MAF Sensor
- Measures the exact air mass entering the engine.
- Helps ECU calculate fuel injection accurately.
- Improves fuel economy and engine performance.
- Reduces emissions.
- Helps stabilize idle speed.
Location of the MAF Sensor
- Installed in the air intake tube between air filter and throttle body.
- Usually located right after the air filter box.
Symptoms of a Faulty MAF Sensor
- Poor acceleration.
- Engine hesitation or jerking.
- Increased fuel consumption.
- Rough idle or engine stalling.
- Black smoke from exhaust.
- Check Engine Light ON.
OBD-II Trouble Codes Related to MAF
- P0100 – MAF circuit malfunction
- P0101 – MAF range/performance problem
- P0102 – MAF low input
- P0103 – MAF high input
- P0104 – MAF intermittent signal
MAF Sensor Electrical Circuit
Most MAF sensors use 3 to 5 wires depending on type:
- 5V or Battery Voltage (12V) power supply
- Ground
- Signal output to ECU
- (Some types include Intake Air Temperature sensor inside)
The sensor uses a heated wire or film that changes resistance based on airflow.
Voltage / Signal Values
- Idle: about 0.8V – 1.5V (or low grams/sec reading)
- Acceleration: voltage/flow increases steadily
- High RPM: higher airflow signal (up to 4.5V depending on system)
Types of MAF Sensors
- Hot Wire MAF Sensor
- Hot Film MAF Sensor
- Kármán Vortex MAF (older systems)
Repair / Replacement Cost
- Cleaning: low cost (MAF cleaner spray)
- Wiring repair: depends on diagnosis
- Replacement: approximately $40 – $250 depending on vehicle
Important Notes
A dirty MAF sensor can often be cleaned instead of replaced. Also, vacuum leaks or intake leaks can cause similar symptoms, so proper OBD diagnosis is necessary before replacement.