P0101

DTC P0101

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 voltage signal in order to provide the correct fuel delivery for a reduction in emissions. The ECM uses the MAF sensor signal in order to control fuel delivery until a calibrated amount of engine air flow is attained. The MAF sensor has an ignition 1 voltage circuit, a signal circuit and a low reference circuit. The MAF sensor produces an output voltage based on inlet air flow through the air induction system. This output voltage will display on the scan tool as a grams per second (g/s) value. The ECM will calculate a predicted MAF value. The ECM compares the actual MAF sensor voltage signal to the predicted MAF value. This comparison will determine if the signal is stuck, or is too low or too high for a given operating condition. DTC P0101 will set if the actual MAF sensor voltage signal is not within a predetermined range of the calculated MAF value.

Conditions for Running the DTC

- DTC P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0234, P0236, P0237, P0238, P0335, P0336, or P1345 are not set.
- The ignition 1 signal is between 9-18 volts.
- The engine speed is less than 2,500 RPM.
- The engine speed is steady within a range of 50 RPM.
- The accelerator pedal position (APP) indicated angle is less than 50 percent.
- The above conditions are present for more than 2 seconds.

Conditions for Setting the DTC

The ECM detects that the actual MAF sensor voltage signal is not within a predetermined range of the calculated MAF value for more than 2 seconds.

Action Taken When the DTC Sets- California

- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Action Taken When the DTC Sets- Federal

- The control module stores the DTC information into memory when the diagnostic runs and fails.
- The malfunction indicator lamp (MIL) will not illuminate.
- The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
- The driver information center, if equipped, may display a message.

Conditions for Clearing the MIL/DTC- California

- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Use a scan tool in order to clear the MIL and the DTC.

Conditions for Clearing the MIL/DTC- Federal

- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
- Use a scan tool in order to clear the MIL and the DTC.

Diagnostic Aids

Inspect for the following conditions:

- Any unmetered air--Any unmetered air that enters the engine downstream of the MAF sensor may cause this DTC to set.
- A sluggish or unresponsive MAF sensor--A short between the signal circuit of the MAF sensor and the signal circuit of the intake air temperature (IAT) sensor. This will cause the MAF sensor to have a very limited output voltage range.
- A malfunctioning MAF sensor can cause excessive engine emissions.
- An open on the 5-volt reference circuit of the barometric pressure sensor (BARO) may cause this DTC to set.
- A short to ground on the signal circuit of the BARO sensor may cause this DTC to set.
- The signal circuit of the BARO sensor shorted to 5 volts may cause this DTC to set.
- An open signal circuit of the BARO sensor may cause this DTC to set.
- The MAF display should increase from 42-50 g/s at idle to 420 g/s or more at the 2-3 shift during a wide-open throttle (WOT) acceleration. If not, inspect for a restriction in the induction system or the exhaust system.
- If the vehicle condition is intermittent, refer to Intermittent Conditions.