P0101

CIRCUIT DESCRIPTION
The Mass Air Flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The Powertrain Control Module (PCM) uses the MAF sensor frequency 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 the inlet air flow through the sensor bore. The PCM uses the Manifold Absolute Pressure (MAP), the Throttle Position (TP), and the engine RPM in order to calculate a predicted MAF value. The PCM compares the actual frequency signal of the MAF sensor 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 frequency signal is not within a predetermined range of the calculated MAF value.

CONDITIONS FOR RUNNING THE DTC
^ The engine speed is more than 250 RPM.
^ The ignition 1 signal is at least 9 volts and no more than 18 volts.
^ The TP sensor angle is no more than 50 percent.
^ The TP sensor angle is steady within a range of no more than 1.5 percent.
^ The MAP sensor is steady within a range of no more than 3 kPa.
^ The Evaporative Emission (EVAP) Purge Solenoid command is less than 100 percent.
^ The Exhaust Gas Recirculation (EGR) position sensor is less than 100 percent.
^ All of the above conditions are present for at least 5 seconds.

CONDITIONS FOR SETTING THE DTC
^ The actual MAF sensor frequency signal is not within a predetermined range of the calculated MAF value.
^ The above conditions are present for at least 5 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM illuminates the Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the diagnostic has run and failed.
^ The PCM stores the conditions which were present when the DTC set as Freeze Frame/Failure Records data.
^ The PCM calculates an airflow value based on the following conditions:
^ The Idle Air Control (IAC) valve position
^ The throttle position
^ The engine RPM
^ The barometric pressure

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM turns the MIL OFF after 3 consecutive trips in which the diagnostic has been run and passed.
^ The history DTC clears after 40 consecutive warm-up cycles have occurred without a malfunction.
^ Use the scan tool in order to clear the DTCs.

DIAGNOSTIC AIDS
^ Inspect for the following conditions:
- A misrouted harness. Inspect the MAF sensor harness in order to ensure that the harness is not routed too closely to the following components:
- The ignition cassettes
- Any solenoids
- Any relays
- Any motors
- A skewed or stuck TP sensor
- The throttle plate sticking or 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 Mass Air Flow value displayed on a scan tool to increase from about 4-7 gm/s at idle to 100 gm/s or more at the time of the 1-2 shift. If not, inspect for a restriction.
- A skewed or unresponsive MAP sensor due to poor vacuum connections, or a damaged vacuum source
- If you suspect the vehicle problem 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 1-5:

Steps 6-14:

Steps 15-25:

The numbers below refer to the step numbers on the diagnostic table.
2. Diagnose any MAF, MAP, TP, or system voltage DTCs before using this table. If a misfire condition exists or a rough running condition is observed with or without DTC P0300 set, proceed to DTC P0300 first.
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 more than 6 volts indicates a malfunction in the wiring or a poor connection.