P0102
DTC P0102 Mass Air Flow (MAF) Sensor Circuit Low Frequency
Circuit Description
The mass air flow (MAF) sensor is an air flow meter. The controls module (PCM/VCM) supplies the MAF sensor a signal circuit. An ignition voltage is supplied to the MAF sensor by an independent circuit. A ground is supplied to the MAF sensor by an independent circuit. The MAF sensor heats a wire element, or grid, within the MAF sensor in order to a calculated temperature. As inlet air flows across and cools the grid, the MAF sensor increases current flow to the grid in order to maintain a constant grid temperature. The MAF sensor converts the grid current flow into a frequency signal. The controls module converts the MAF signal frequency into a grams per second value. During low air flow rates, such as at engine idle, the MAF sensor produces a low frequency signal. During high air flow rates, such as wide open throttle-road load, the MAF sensor increases the frequency signal. The controls module monitors the MAF sensor signal frequency to calculate the flow and mass of the air entering the engine.
This DTC is designed to detect an unusually low MAF sensor signal frequency. If a MAF sensor frequency is detected by the VCM below 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 speed is more than 300 RPM.
- The system voltage is more than 8 volts.
Conditions for Setting the DTC
The MAF frequency is 10 Hz or less for more than 1 second.
Action Taken When the DTC Sets
- The control module illuminates the malfunction indicator lamp (MIL) if a failure is detected during 2 consecutive key cycles.
- The control module sets the DTC and records the operating conditions at the time the diagnostic failed. The failure information is stored in the scan tool's Freeze Frame and Failure Records.
Conditions for Clearing the MIL/DTC
- The control module 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. A warm up cycle occurs when the coolant temperature has risen 22° C (40° F) from the startup coolant temperature and the engine coolant reaches a temperature that 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 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 the connectors and the wiring harnesses related to the MAF sensor. A change in the display indicates the location of the fault.
- A plugged intake air duct or filter element. A wide open throttle acceleration from a stop should cause the Mass Air Flow displayed on a scan tool to increase from about 4 - 7 g/s at idle to 100 g/s or more at the time of the 1 - 2 shift. If not, check for a restriction.
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 Testing for Intermittent and Poor Connections.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs.
Steps 1 - 2:
Steps 3 - 5:
Steps 6 - 10:
Steps 11 - 16:
Steps 17 - 18:
Test Description
The numbers below refer to step numbers on the diagnostic table.
2. This step verifies that the problem is present at idle.
6. A voltage reading of less than 4 or more than 6 volts at the MAF sensor signal circuit indicates a malfunction in the wiring or a poor connection.
7. This step verifies that the ignition feed voltage and a good ground are available at the MAF sensor.
11. This step determines if the fuse is open. If the fuse is open, locate and repair the short to ground in the ignition positive voltage circuit.