The mass airflow (MAF) sensor measures the speed and density of air entering the intake manifold. The ECM converts this input to a mass of air per unit time to correctly fuel the engine. The MAF output voltage is a function of the power required to keep the sensing element at a fixed temperature above outside air temperature as the incoming air-cools the sensing elements. The output voltage varies between 0.14 and 4.8 volts under all normal engine running conditions. As a validity check, the ECM calculates airflow based on engine speed and throttle valve position from the TP sensors and compares this to the actual reading from the MAF sensor. DTC P0101 will set if the ECM determines the calculated airflow value and actual airflow value are not within a calibrated range.

DTC P0101 will set if the MAF sensor airflow value is too far out of agreement from the ECM calculated airflow value (based on engine speed and TP sensors) when:

DTC P0101 diagnostic runs continuously once the above conditions have been met.

P0101 is a (type B) DTC.

Important: If an electrical fault is present (open, short to ground, or short to voltage) on MAF sensor signal circuit 492, DTC P0101 will become active while the electrical circuit fault condition is present.

Using Scan tool, verify MAF reads 0.0 g/s with ignition On and engine Off.

Check the following for possible causes of MAF rationality errors: