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 the hot wires at a constant temperature. MAF sensor converts the changes in current draw to a frequency signal read by the PCM. PCM calculates airflow (grams per second) based on this signal.

PCM monitors the MAF sensor frequency and can determine if sensor is stuck low, stuck high, not providing the airflow value expected for a given operating condition, or that the 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.