P0101

DTC P0101 Mass Air Flow System Performance (1 Of 3):

DTC P0101 Mass Air Flow System Performance (2 Of 3):

DTC P0101 Mass Air Flow System Performance (3 Of 3):

Mass Air Flow System:

Circuit Description
The Mass Air Flow (MAF) sensor measures the amount of air entering the engine during a given time. The Vehicle Control Module (VCM) uses the mass air flow information for fuel delivery calculations. A large quantity of air entering the engine indicates an acceleration or high load situation. A small quantity of air indicates deceleration or idle.

The MAF sensor produces a frequency signal which can be monitored using a scan tool. The frequency varies within a range of around 5 to 7 g/s at idle to near 125 g/s at maximum engine load. This DTC sets if the signal from the MAF sensor does not match a predicted value based on the barometric pressure, the throttle position and the engine speed. This DTC is a type A DTC.

Conditions For Setting The DTC
The Following Conditions will set the DTC:

^ The engine is running.
^ No Throttle Position (TP) sensor DTCs.
^ No Manifold Absolute Pressure (MAP) sensor DTCs.
^ No Evaporation Emission (EVAP) DTCs.
^ Exhaust Gas Recirculation (EGR) DTC P0401 not active.
^ MAF DTCs P0101 or P0103 not active.
^ The system Voltage is greater than 10.0 volts but less than 17.0 volts.
^ The Canister Purge Duty Cycle is less than 99%.
^ The change in throttle position is less than 3.9%.
^ The EGR duty cycle is no more than 89.9%.
^ The EGR Pintle Position is no more than 89.9%.
^ The MAP is no more than 90 kPa.
^ The throttle position is no more than 89.8%.
^ The above conditions met for greater than 2 seconds.
^ The change in MAF sensor is greater than a calculated value.

Action Taken When The DTC Sets

^ The VCM illuminates the Malfunction Indicator Lamp (MIL) the first time the fault is detected.
^ The VCM calculates an airflow value based on idle air control valve position, throttle position, engine speed and barometric pressure.
^ The VCM will store the conditions which were present when the DTC set as Freeze Frame and the Fail Records data.

Conditions For Clearing The MIL/DTC

^ The VCM turns the MIL off on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.
^ A history DTC clears after 40 consecutive warm-up cycles have occurred without a fault.
^ Using the scan tool Clear Info function or disconnecting the VCM battery feed clears the DTC.

Diagnostic Aids
Check for the following conditions:

^ A slewed or stuck Throttle Position (TP) sensor. A faulty TP sensor or TP sensor circuit can cause the VCM to incorrectly calculate the predicted mass air flow value. Observe the Throttle Angle with the throttle closed. If the Throttle Angle reading is not 0%, check for the following conditions:

- The throttle plate sticking or excessive deposits on the throttle plate or the throttle bore.
- The TP sensor signal circuit shorted to voltage.
- A Poor connection or high resistance in the TP sensor ground circuit.
- If none of the above conditions are noted and the Throttle Angle reading at closed throttle is not 0%, replace the TP sensor.

^ Repair as necessary.
^ A poor connection at VCM. Inspect harness connectors for the following conditions:

- Backed out terminals.
- Improper mating.
- Broken locks.
- Improperly formed or damaged terminals.
- Poor terminal to wire connection.

^ A misrouted harness. Inspect the MAF sensor harness in order to ensure that it is not routed too close to high voltage wires such as spark plug leads.
^ A damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving the connectors and the wiring harnesses related to the MAF sensor. A change in the display indicates the location of the fault.
^ A plugged intake air duct or dirty air filter element. A wide open throttle acceleration from a stop should cause the Mass Air Flow displayed on a scan tool to increase from about 4-7 gm/s at idle to 100 gm/s or greater at the time of the 1-2 shift. If not, check for a restriction.
^ Slewed MAP sensor. A slewed MAP sensor can cause the Barometric Pressure (BARO) reading to be incorrectly calculated. In order to check the MAP sensor, compare the BARO reading on the vehicle being diagnosed to the BARO reading on a normally operating vehicle. If a large difference is noted (over 8 kPa), replace the MAP sensor.

Test Description
The numbers below refer to the step numbers on the diagnostic table.

2. This step verifies that the problem is present at idle.
5. A voltage reading of less than 4.0 volts or over 6.0 volts at the MAF sensor signal circuit indicates a fault in the wiring or a poor connection.
6. This step verifies that the ignition feed circuit voltage and a good ground are available at the MAF sensor.