Air Flow Meter/Sensor: Testing and Inspection

MASS AIR FLOW SENSOR (MAF SENSOR)
This hot film type air flow sensor is composed of a hot film sensor, housing, and a metering duct (hybrid, sensor element). The mass airflow rate is measured by detection of heat transfer from a hot film probe. A change in the mass air flow rate will cause a change in the amount of heat being transferred from the hot film probe surface to the air flow. This results in a change in temperature of the hot film probe and a change of resistance.

Circuit Diagram:

TROUBLESHOOTING HINTS
1. If the engine occasionally, stalls crank the engine and shake the MAF sensor harness. If the engine stalls, check the poor contact of the MAF sensor connector.
2. If the MAF sensor output voltage is other than 0 when the ignition switch is turned on (do not start the engine), check for a faulty MAF sensor or ECM.
3. If the engine can idle even though the MAF sensor output voltage is out of specification, check for the following conditions:
- Disturbed air flow in the MAF sensor.
- Disconnected air duct, clogged air cleaner filter.
- Poor combustion in the cylinder.
- Faulty spark plugs, ignition coil, injectors, incorrect comparison.
- Air leak in the intake manifold

4. Though no MAF sensor malfunction occurs, check the mounting direction of the MAF sensor.

Using Hi-Scan:

Using Voltmeter:

NOTE: When the vehicle is new (within initial operation of about 500 km - 300 miles), the mass air flow sensor air quantity may be about 10% higher.

Harness Inspection Procedures: