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 received from sensor under certain conditions using engine speed (RPM), throttle position, and altitude 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.
• TP sensor angle less than 50 percent.
• System voltage greater than 8 volts.
• MAF signal frequency less than 1200 Hz.
• Conditions present for at least 0.5 second, plus 400 3X reference periods (133 crankshaft revolutions).