Symptoms

- Engine stall - Engine running rough - Excessive fuel consumption - Excessive smoke - Engine Light ON (or Service Engine Soon Warning Light)

Possible Causes

- Dirty mass air flow sensor - Dirty mass air filter - Mass air flow sensor harness is open or shorted - Mass air flow sensor electrical circuit poor connection - Intake air leaks - Faulty mass air flow sensor

When Detected

An excessively high voltage from the sensor is sent to Engine Control Module (ECM).

Tech Notes

Before replacing the mass air flow sensor, try replacing the air filter and cleaning the air flow sensor with low compress air or mass air flow sensor cleaner. Reset code and drive vehicle. If the code comes back, it may be necessary to replaced the mass air flow sensor.

Description

The Mass Air Flow (MAF) sensor is placed in the stream of intake air. It measures the intake flow rate by measuring a part of the entire intake flow. It consists of a hot film that is supplied with electric current from the Engine Control Module (ECM). The temperature of the hot film is controlled by the ECM acertain amount. The heat generated by the hot film is reduced as the intake air flows around it. The more air, the greater the heat loss. Therefore, the ECM must supply more electric current to maintain the temperature of the hot film as air flow increases. The ECM detects the air flow by means of this current change.