Circuit Description

The mass air flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The engine control module (ECM) uses the MAF sensor signal to provide the correct fuel delivery for all engine speeds and loads. A small quantity of air entering the engine indicates a deceleration or idle condition. A large quantity of air entering the engine indicates an acceleration or high load condition. The MAF sensor has the following circuits:

• An ignition 1 voltage circuit
• A ground circuit
• A signal circuit

The ECM applies a voltage to the sensor on the signal circuit. The sensor uses the voltage to produce a frequency based on the inlet air flow through the sensor bore. The frequency varies within a range of near 2,000 Hertz at idle to near 11,500 Hertz at maximum engine load. The ECM uses the following sensor inputs to calculate a predicted MAF value:

• The manifold absolute pressure (MAP) estimated
• The intake air temperature (IAT) sensor
• The throttle areas from the electronic throttle control (ETC) and IAT, barometric pressure (BARO), and the estimated MAP

The ECM compares the actual MAF sensor frequency signal to the predicted MAF value. This comparison will determine if the signal is stuck too low or too high for a given operating condition. If the ECM detects the actual MAF sensor frequency signal is too high of a delta from the calculated MAF value and a MAP modeled signal is too high of a delta from measured MAP, the DTC P0101 sets.