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HOMESERVICE MANUALSCHEVROLET2001CHEVY EXPRESS G2500, VAN CARGO EXTENDED, 5.7 R, L31/KL8REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 214 (ENGINE CONTROLS SELF-DIAGNOSTICS - 3.4L)DIAGNOSTIC TESTSDTC P0101: MAF SENSOR PERFORMANCEDIAGNOSTIC PROCEDURES
2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8

Diagnostic Procedures

2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8SECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2003 Pontiac Grand Am, 2003 Oldsmobile Alero, 2003 Chevrolet Monte Carlo, and 2003 Chevrolet Impala. 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  6.
  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 data for this DTC. Turn ignition switch to OFF position for 30 seconds. Start the engine. Operate the vehicle within the Conditions For Running or as close to the Freeze Frame/Failure Records data that you observed. See CONDITIONS FOR RUNNING . Does the DTC fail this ignition? If yes, go to next step. If no, see 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.
  5. Turn ignition switch to RUN position, engine OFF. Observe the MAP sensor parameter using a scan tool. The MAP sensor pressure should be within the specified range for your altitude. See ALTITUDE VS. BAROMETRIC PRESSURE  table. 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 ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO 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, diagnose MAP sensor. See MANIFOLD ABSOLUTE PRESSURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO 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 ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO 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 (WOT) using a scan tool. Does the TP sensor parameter change from zero 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 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 ECT sensor.
    • Any type of restriction in the exhaust system. See RESTRICTED EXHAUST under EXHAUST SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO 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 ignition 1 voltage circuit of the MAF sensor and a good ground. Connect a DMM to the probe of the test light and a good ground. Is the voltage less than battery voltage? If yes, go to step  12. If no, go to next step.
  11. Check 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 next step.
  14. Use the scan tool to clear the DTCs. Turn ignition switch to OFF position for 30 seconds. Start the engine. Operate the vehicle within the Conditions For Running. See CONDITIONS FOR RUNNING . 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. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay at this time.
ALTITUDE VS. BAROMETRIC PRESSURE

(1) Altitude Measured - Feet (Meters) Barometric Pressure - kPa
14000 (4267) 56-64
13000 (3962) 58-66
12000 (3658) 61-69
11000 (3353) 64-72
10000 (3048) 66-74
9000 (2743) 69-77
8000 (2438) 71-79
7000 (2134) 74-82
6000 (1829) 77-85
5000 (1829) 80-88
4000 (1219) 83-91
3000 (914) 87-95
2000 (610) 90-98
1000 (305) 94-102
0 (0) 96-104
-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.