Circuit Description

Mass Airflow (MAF) sensor measures amount of air entering engine during a given time. PCM uses MAF sensor information for fuel delivery calculations. MAF sensor readings during acceleration are much higher than those during deceleration or idle.

PCM calculates what MAF sensor reading should be from sensor under certain conditions using engine speed (RPM), throttle position, and barometric pressure parameters. When these test conditions are met, PCM will compare its calculated MAF value to actual value received from sensor.

Conditions required to set DTC are:

• Engine running.
• System voltage between 9-16 volts.
• Throttle is steady and TP angle is less than 50 percent.
• EGR duty cycle is less than 50 percent.
• EGR pintle position is less than 50 percent.
• MAF signal frequency indicates an airflow significantly higher or lower than a predicted value based on BARO pressure, throttle position and engine RPM.
• Conditions present for at least 12 seconds.