Circuit Description

Mass Airflow (MAF) sensor is hot-wire type and is used to measure airflow rate into engine. MAF sensor has a battery feed, ground and signal circuit. As airflow increases, a greater amount of current is required to maintain hot wires at a constant temperature. MAF sensor converts changes in current draw to a frequency signal read by PCM. PCM calculates airflow (grams per second) based on this signal.

PCM monitors MAF sensor frequency and can determine if sensor is stuck low, stuck high, not providing airflow value expected for a given operating condition, or that signal variation expected during normal operation is not present.

This test checks for a stuck MAF sensor signal. If MAF sensor frequency varies less than a predetermined minimum amount, DTC will set.

DTC will set when following conditions are present:

• DTC P0102, P0103, P0107, P0108, P0121, P0122, P0123, P1120, P1220 or P1221 not set.
• Engine running.
• Engine speed 50-2800 RPM.
• TP sensor angle less than 50 percent when BARO-MAP is greater than 65 kPa.
• Ignition voltage 10-16 volts.
• MAF frequency 50 percent different from speed density calculation.
• Change in TP sensor is less than 3 percent.
• Conditions stable for 2 seconds.
• Conditions met for 5 seconds.