P0102

DTC P0102

CIRCUIT DESCRIPTION
The mass air flow (MAF) sensor is an airflow meter that measures the amount of air entering the engine. The powertrain control module (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 a deceleration or idle. 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 in order to produce a frequency based on inlet air flow through the sensor bore. The frequency varies within a range of around 2,000 Hertz at idle to about 10,000 Hertz at maximum engine load. If the PCM detects a frequency signal lower than the possible range of a properly operating MAF sensor, DTC P0102 sets.

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC P0102 Mass Air Flow (MAF) Sensor Circuit Low Frequency

CONDITIONS FOR RUNNING THE DTC
- The engine is running for more than 2 seconds.
- The engine speed is more than 400 RPM.
- The ignition 1 signal is more than 8 volts.
- The above conditions are met for more than 1 second.
- DTC P0102 runs continuously when the above conditions are met.

CONDITIONS FOR SETTING THE DTC
The PCM detects that the MAF sensor frequency signal is less than 1,200 Hertz for more than 0.6 second.

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:
- An incorrectly routed harness-Inspect the harness of the MAF sensor in order to verify that it is not routed too close to the following components:
- The secondary ignition wires or coils
- Any solenoids
- Any relays
- Any motors
- Any aftermarket accessories
- 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 parameter on the scan tool to increase rapidly. This increase should be from 6-12 g/s at idle to 230 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 15 ohms or more on the ground circuit or the ignition 1 circuit of the MAF sensor can cause this DTC to set.

If the condition is intermittent, refer to Testing for Intermittent Conditions and Poor Connections. Component Tests and General Diagnostics

TEST DESCRIPTION

Step 1 - Step 7:

Step 8 - Step 13:

Step 14 - Step 23:

Step 24 - Step 29:

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.
7. This voltage drop test will determine if high resistance has caused this DTC to set.
9. This step verifies the voltage signal from the PCM to the MAF sensor connector.
10. This step tests the signal circuit of the MAF sensor for a short to another 5-Volt reference circuit.
11. This step will determine if the PCM is able to process the frequency signal that it receives from the MAF sensor.
14. This step will determine which portion of the circuit or which component is shorted to ground.
17. This step verifies that the signal circuit is not shorted to any other PCM circuit.