DTC P0101: MAF System Performance: Description

The Mass Airflow (MAF) sensor is an airflow meter that measures the amount of air entering the engine. The Powertrain Control Module (PCM) uses the MAF sensor signal in order to provide the correct fuel delivery for a wide range of engine speeds and loads. A small quantity of air entering the engine indicates a deceleration or idle. 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 PCM applies a voltage to the sensor on the signal circuit. The sensor uses the voltage in order to produce a frequency based on inlet air flow through the sensor bore. The frequency varies within a range of around 2,000 Hertz at idle to about 10,000 Hertz at maximum engine load. The PCM uses the following sensor inputs in order to calculate a predicted MAF value:

• The Barometric (BARO) pressure at key on.
• The Manifold Absolute Pressure (MAP).
• The Intake Air Temperature (IAT).
• The Engine Coolant Temperature (ECT).
• The Throttle Position (TP).
• The engine speed (RPM).

The PCM 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. DTC P0101 sets if the actual MAF sensor frequency signal is not within a predetermined range of the calculated MAF value.