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HOMESERVICE MANUALSCHEVROLET2001CHEVY EXPRESS G2500, VAN CARGO EXTENDED, 5.7 R, L31/KL8REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 213 (ENGINE CONTROLS SELF-DIAGNOSTICS - 3.1L ENGINE)DIAGNOSTIC TESTSDTC P0101: MAF SENSOR PERFORMANCEDIAGNOSTIC PROCEDURE
2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8

Diagnostic Procedure

2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8SECTION Diagnostic Procedure
WARNING: This page is about a different car, the 2003 Pontiac Grand Prix, 2003 Chevrolet Malibu, and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
  2. Attempt to start the engine. Does the engine start? If yes, go to next step. If no, go to step  4.
  3. Observe the Diagnostic Trouble Code (DTC) Information using the scan tool. Does the scan tool display any other DTCs set? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, go to next step.
  4. Observe the Freeze Frame/Failure Records for this DTC. Turn ignition switch to OFF position for 30 seconds. Start the engine. Operate the vehicle within the Conditions For Running Test. See CONDITIONS FOR RUNNING TEST . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to next step. If no, go to DIAGNOSTIC AIDS .
    5. NOTE: The Altitude vs. Barometric Pressure table indicates a pressure range for a given altitude under normal weather conditions. Weather conditions consisting of very low or very high pressure and/or temperature may cause a reading to be slightly out of range. See ALTITUDE VS. BAROMETRIC PRESSURE  table.
  5. Turn ignition switch to RUN position, engine OFF. Observe the Manifold Absolute Pressure (MAP) sensor parameter using the scan tool. The MAP sensor pressure should be within the specified range for your altitude. Is the MAP sensor pressure within the specified range as indicated on the Altitude vs Barometric Pressure table? If yes, go to next step. If no, go to MANIFOLD ABSOLUTE PRESSURE SENSOR under SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - 3.1L CENTURY, GRAND PRIX & MALIBU article.
  6. Start the engine. Turn OFF all accessories. Allow the engine to reach operating temperature. Observe the MAP sensor parameter using a scan tool. Is the MAP sensor parameter 0.8-2.0 volts? If yes, go to next step. If no, go to MANIFOLD ABSOLUTE PRESSURE SENSOR under SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - 3.1L CENTURY, GRAND PRIX & MALIBU article.
  7. Idle the engine. Observe the MAP sensor parameter using a scan tool. Increase the engine speed slowly to 3000 RPM and then back to idle. Does the MAP sensor parameter change smoothly and gradually through the specified range of the test? If yes, go to next step. If no, go to MANIFOLD ABSOLUTE PRESSURE SENSOR under SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - 3.1L CENTURY, GRAND PRIX & MALIBU article.
  8. Turn ignition switch to OFF position for 30 seconds. Turn ignition switch to RUN position, engine OFF. Observe the TP sensor parameter at closed throttle using a scan tool. Depress the accelerator pedal completely. Observe the TP sensor parameter at wide open throttle using a scan tool. Does the TP sensor parameter change from zero percent to 100 percent? If yes, go to next step. If no, go to DTC P0121: TP SENSOR PERFORMANCE .
  9. Turn ignition switch to OFF position. Check 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 Mass Airflow (MAF) sensor.
    • Any contamination or debris on the sensing elements of the MAF sensor.
    • Any water intrusion in the induction system.
    • Any vacuum leak downstream of the MAF sensor.
    • A skewed or stuck Engine Coolant Temperature (ECT) sensor
    • Any type of restriction in the exhaust system. Go to EXHAUST RESTRICTION under EXHAUST SYSTEM CHECK under EMISSION SYSTEM & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 3.1L CENTURY, GRAND PRIX & MALIBU article.

    Did you find and correct the condition? If yes, go to step  14. If no, go to next step.

  10. Disconnect the MAF sensor harness connector. Turn ignition switch to RUN position, engine OFF. Connect a test light between the MAF sensor ignition 1 voltage circuit and a good ground. Connect a DMM to the test light probe and a good ground. Is the voltage within 0.50 volts of battery voltage? If yes, go to next step. If no, go to step  12.
  11. Test for an intermittent and for a poor connection at the MAF sensor. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  12. Repair the high resistance in the ignition 1 voltage circuit of the MAF sensor. After repair, go to step  14.
  13. Replace the MAF sensor. After repair, go to step  14.
  14. Clear the DTCs using a scan tool. Turn ignition switch to OFF position for 30 seconds. Start the engine. Operate the vehicle within the Conditions For Running Test. See CONDITIONS FOR RUNNING TEST . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to step  2. If no, go to next step.
  15. Using the scan tool, observe the stored information in CAPTURE INFO. Are there any DTCs that have not been diagnosed? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay at this time.
(1) ALTITUDE VS. BAROMETRIC PRESSURE

Altitude - Meters Altitude - Feet Barometric Pressure - kPa
4267 14000 56-64
3962 13000 58-66
3658 12000 61-69
3353 11000 64-72
3048 10000 66-74
2743 9000 69-77
2438 8000 71-79
2134 7000 74-82
1829 6000 77-85
1524 5000 80-88
1219 4000 83-91
914 3000 87-95
610 2000 90-98
305 1000 94-102
0 0 (Sea Level) 96-104
-305 -1000 101-105
(1) Determine your altitude by contacting a local weather station or by using another reference source.
RENDER: 1.0x

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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.