Circuit/System Description

The mass air flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The control module 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 MAF sensor signal circuit
• A ground circuit

The control module 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 10,000 Hertz at maximum engine load. The control module uses the following sensor inputs to calculate a predicted MAF value:

• The barometric pressure (BARO) at key ON
• The manifold absolute pressure (MAP) sensor
• The intake air temperature (IAT) sensor
• The engine coolant temperature (ECT) sensor
• The throttle position indicated angle
• The engine speed (RPM)

The control module compares the actual MAF sensor frequency signal to the predicted MAF value. This comparison will determine if the signal is stuck based on a lack of variation, or is too low or too high for a given operating condition. If the control module detects the actual MAF sensor frequency signal is not within a predetermined range of the calculated MAF value, DTC P0101 sets.