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HOMESERVICE MANUALSCHEVROLET2001CHEVY EXPRESS G2500, VAN PASSENGER EXTENDED, 5.0 MREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 221 (ENGINE CONTROLS SELF-DIAGNOSTICS)DIAGNOSTIC TESTSDTC P0102: MAF SENSOR CIRCUIT - LOW FREQUENCYDIAGNOSTIC PROCEDURES
2001 Chevrolet Chevy Express G2500, Van Passenger Extended, 5.0 M

Diagnostic Procedures

2001 Chevrolet Chevy Express G2500, Van Passenger Extended, 5.0 MSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2003 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Start the engine. Observe MAF sensor frequency with a scan tool. Is MAF sensor frequency less than 1200 Hz? If yes, go to step  4. If no, go to next step.
  3. Observe the Freeze Frame/Failure Records data for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition cycle? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
  4. Observe MAF sensor frequency with a scan tool. Move the harness and connector of the MAF sensor. Does movement of the harness or connector affect the MAF sensor frequency? If yes, go to step  18. If no, go to next step.
  5. Turn ignition OFF. Inspect for the following conditions:
    • A restricted or collapsed air intake duct.
    • A misaligned air intake duct.
    • A dirty or deteriorating air filter element.
    • Any objects blocking the air inlet screen of the MAF sensor.
    • Any contamination or debris on the sensing elements of the MAF sensor.

    Did you find and correct the condition? If yes, go to step  26. If no, go to next step.

  6. Inspect the fuse in the MAF sensor ignition 1 voltage circuit. Is the fuse open? If yes, go to step  12. If no, go to next step.
  7. Turn ignition ON, with engine OFF. Disconnect MAF sensor harness connector. Test the voltage between the MAF sensor ignition 1 voltage circuit and a good ground. Is voltage less than battery voltage? If yes, go to step  19. If no, go to next step.
    8. NOTE: All electrical components and accessories must be turned off.
  8. Turn ignition OFF. Allow 60 seconds for the control modules to power down. Measure the resistance between the MAF sensor harness connector ground circuit and a good ground. Is the resistance less than 5 ohms? If yes, go to next step. If no, go to step  20.
  9. Turn ignition ON, with engine OFF. Measure the voltage between the MAF sensor signal circuit and a good ground. Is the voltage within 4.8-5.2 V? If yes, go to next step. If no, go to step  11.
  10. Connect a 3-amp fused jumper wire between the MAF sensor signal circuit and a good ground. Start the engine and observe the DTC Information with a scan tool. Do any additional DTCs set? If yes, go to step  22. If no, go to step  16.
  11. Is the voltage less than 4.5 V? If yes, go to step  13. If no, go to step  14.
    12. NOTE: The MAF sensor ignition 1 voltage circuit is spliced to other components of the vehicle.
  12. Test the ignition 1 voltage circuit for a short to ground. Did you find and correct the condition? If yes, go to step  26.
  13. Turn ignition OFF and disconnect the PCM. Test the signal circuit between the PCM and MAF sensor for a short to ground, an open or high resistance. Did you find and correct the condition? If yes, go to step  26. If no, go to step  15.
    14. NOTE: Disconnecting the PCM connectors may eliminate the short to voltage if the signal circuit is shorted to another PCM circuit.
  14. Turn ignition OFF and disconnect the PCM. Turn ignition ON, with engine OFF. Measure the voltage from the MAF sensor signal circuit to a good ground. Is the voltage greater than 0 V? If yes, go to step  21. If no, go to next step.
  15. Measure the resistance between the MAF sensor signal circuit and all other circuits at both PCM connectors. Is the resistance less than infinity? If yes, go to step  23. If no, go to step  17.
  16. Test for an intermittent and/or poor connections at the MAF sensor. Did you find and correct the condition? If yes, go to step  26. If no, go to step  24.
  17. Test for an intermittent and/or poor connections at the PCM. Did you find and correct the condition? If yes, go to step  26. If no, go to step  25.
  18. Repair wiring or connector as needed. Did you complete the repair? If yes, go to step  26.
  19. Repair high resistance or open in the MAF sensor ignition 1 voltage circuit. Did you complete the repair? If yes, go to step  26.
  20. Repair high resistance or open in the MAF sensor ground circuit. Did you complete the repair? If yes, go to step  26.
  21. Repair short to voltage in the MAF sensor signal circuit. Did you complete the repair? If yes, go to step  26.
  22. Repair short between the MAF sensor signal circuit and the circuit for which the DTC set. Did you complete the repair? If yes, go to step  26.
  23. Repair circuits that are shorted together. Did you complete the repair? If yes, go to step  26.
  24. Replace MAF sensor. See MASS AIRFLOW SENSOR under SENSORS in REMOVAL & INSTALLATION - CORVETTE article. Did you complete the replacement? If yes, go to step  26.
  25. Replace PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - CORVETTE article. Did you complete the replacement? If yes, go to next step.
  26. Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition cycle? If yes, go to step  2. If no, go to next step.
  27. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.