P0103

DTC P0102 MAF Sensor Circuit High Frequency




Circuit Description
The Mass Air Flow (MAF) sensor is a hot wire type air flow meter. The MAF sensor uses ignition voltage, a ground and a signal circuit. The signal circuit is the input to the VCM. The MAF heats a wire element in the air flow stream to a predetermined temperature. As inlet air flows across and cools the wire element, the MAF sensor increases current flow to the wire element in order to maintain a constant element temperature. The MAF sensor converts this current flow into a frequency signal. The VCM monitors the MAF signal frequency and determines the flow and mass of the air entering the engine.

The VCM converts the MAF signal frequency into a grams per second value. During low air flow rates (such as at engine idle) the MAF sensor will produce a low frequency signal (approximately 2000 Hz or 6 grams/second). During high air flow rates such as wide open throttle at road load, the MAF sensor will produce a high frequency signal (approximately 9000 HZ or 125 grams/second).

This DTC is designed to detect an unusually high MAF sensor signal frequency. If the VCM detects a MAF signal frequency above the possible range of a normally operating MAF sensor, this DTC will be set.

Conditions for Running the DTC
- The engine is running
- The engine run time is more than 0.4 seconds
- The engine speed is more than 300 RPM
- The system voltage is more than 8 volts

Conditions for Setting the DTC
The MAF frequency is 11000 Hz or more for more than 1 second

Action Taken When the DTC Sets
- The VCM illuminates the MIL (Malfunction Indicator Lamp) if a failure is detected during 2 consecutive key cycles.
- The VCM will set the DTC and records the operating conditions at the time the diagnostic fails. The VCM stores the failure information in the scan tools Freeze Frame and/or the Failure Records.

Conditions for Clearing the MIL/DTC
- The VCM turns OFF the MIL after 3 consecutive drive trips when the test has Run and Passed.
- A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 22 °C (40 °F) from the startup coolant temperature and the engine coolant temperature is more than 70 °C (158 °F) during the same ignition cycle).
- Use the scan tool Clear Information function.

Diagnostic Aids
Check 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 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 connectors and wiring harnesses related to the MAF sensor. A change in the display will indicate the location of the malfunction.

An intermittent may be caused by any of the following conditions:
- A poor connection
- Rubbed through wire insulation
- A broken wire inside the insulation

Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis.

If a repair is necessary, then refer to Wiring Repairs or Connector Repairs.

Steps 1 - 2:

Steps 3 - 6:

Steps 7 - 9:

Steps 10 - 11:

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.
4. A frequency reading with the MAF sensor connector disconnected indicates an Electromagnetic Interference (EMI) related fault or a poor connection.