P0102

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 to provide the correct fuel delivery for all engine speeds and loads. A small quantity of air entering the engine indicates a deceleration or idle condition. 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 to produce a frequency based on inlet air flow through the sensor bore. The frequency varies within a range of near 2,000 Hertz at idle to near 10,000 Hertz at maximum engine load. If the PCM detects a frequency signal less than the possible range of a properly operating MAF sensor, DTC P0102 sets.

CONDITIONS FOR RUNNING THE DTC
- The engine is running for more than 1 second.
- The engine speed is more than 250 RPM.
- The ignition 1 signal is more than 10.5 volts.

CONDITIONS FOR SETTING THE DTC
The PCM detects that the MAF sensor frequency signal is less than 1,135 Hz.

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-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.

DIAGNOSTIC AIDS
- Inspect for the following conditions:
- Inspect the harness of the MAF sensor to verify that it is not routed too close to the following components:
- The ignition cassette
- Any solenoids
- Any relays
- Any motors
- A low minimum air rate through the sensor bore may cause this DTC to set at idle or during deceleration. Inspect for any vacuum leaks downstream of the MAF sensor.
- A wide-open throttle (WOT) acceleration from a stop should cause the MAF sensor g/s display on the scan tool to increase rapidly. This increase should be from 4-7 g/s at idle to 190 g/s or more at the time of the 1-2 shift. If the increase is not observed, inspect for a restriction in the induction system or the exhaust system.
- A resistance of 20 ohms or more on the ground circuit of the MAF sensor can cause this DTC to set.
- If the condition is intermittent, refer to Intermittent Conditions . Intermittent Conditions

TEST DESCRIPTION

Steps 1-3:

Steps 4-6:

Steps 7-11:

Steps 12-14:

Steps 15-18:

Steps 19-26:

Steps 27-31:

The numbers below refer to the step numbers on the diagnostic table.
5. This step will determine if any mechanical faults have caused this DTC to set.
9. This step verifies the signal circuit from the MAF sensor electrical connector to the PCM.
10. This step tests the signal circuit of the MAF sensor for a short to another 5-volt reference circuit.
16. This step verifies that the signal circuit is not shorted to any other PCM circuit.