P0101

CIRCUIT DESCRIPTION
The Mass Air Flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The 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 deceleration or idle. A large quantity of air entering the engine indicates an acceleration or high load situation. The MAF sensor has an ignition 1 voltage circuit, a ground circuit and 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 PCM uses the Manifold Absolute Pressure (MAP), the Intake Air Temperature (IAT) and the engine RPM in order to calculate a predicted MAF value. The PCM compares the actual MAF sensor signal to the predicted MAF value in order to 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 will set if the actual MAF sensor signal is not within a predetermined range of the calculated MAF value.

CONDITIONS FOR RUNNING THE DTC
^ DTCs P0102, P0103, P0106, P0107, P0108, P0121, P0122, P0123, P1121, or P1122 are not set.
^ The engine is running.
^ The Ignition 1 signal is at least 11 volts and no more than 18 volts.
^ The TP sensor angle is less than 95 percent.
^ The TP sensor angle is steady within a range of less than 5 percent.
^ The MAP sensor is less than 80 kPa.
^ The MAP sensor is steady within a range of less than 3 kPa.
^ All of the above conditions are present for greater than 2 seconds.

CONDITIONS FOR SETTING THE DTC
^ The actual MAF sensor signal is not within a predetermined range of the calculated MAF value.
^ The above condition is present for greater than 8 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ 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.

CONDITIONS FOR CLEARING THE MIL/DTC
^ 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-lip 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.

DIAGNOSTIC AIDS
Inspect for the following conditions:
^ A misrouted harness. Inspect the MAF sensor harness in order to ensure that it is not routed too close to the following:
^ The ignition coils
^ The solenoids
^ The relays
^ The motors
^ Excessive deposits on the throttle plate or in the throttle bore.
^ Any unmetered air entering the engine may cause this DTC to set. Ensure that the oil dipstick is fully seated and the oil fill cap is secure.
^ A Wide-Open Throttle (WOT) acceleration from a stop should cause the MAF sensor value displayed on a scan tool to increase from about 4-7 gm/s at idle to 190 gm/s or more at the time of the 1-2 shift. If not inspect for a restriction.
^ A skewed MAP sensor will cause the calculated mass air flow value to be inaccurate. The value shown for the MAP sensor display varies with the altitude. With the ignition ON and the engine OFF, 103 kPa is the approximate value displayed at or near sea level. The value decreases by approximately 3.0 kPa for every 1,000 feet of altitude.
^ High resistance on the MAP sensor signal circuit may cause this DTC to set.

If you suspect the vehicle condition may be related to aftermarket accessories, refer to Checking Aftermarket Accessories in Diagrams. Service Precautions

If the problem is intermittent, refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Steps 1-6:

Steps 7-16:

Steps 17-24:

The numbers below refer to the step numbers on the diagnostic table.
5. Any unmetered air entering the engine may cause this DTC to set. This step eliminates any conditions which can cause a DTC to set with a normally operating MAF sensor.
10. This step verifies the signal circuit from the MAF sensor electrical connector to the PCM. A voltage reading of less than 4 volts or greater than 6 volts indicates a malfunction in the wiring or a poor connection.