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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 141 (Engine Controls Self-Diagnostics - 5.7L - Bi-Fuel) >> Diagnostic Tests >> DTC P0101: Mass Air Flow Sensor Performance >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, and 2002 Chevrolet Chevy Express. 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. Capture the DTC information from the Alternative Fuels ECM into the scan tool. Inspect BOTH the Alternative Fuels ECM and the PCM for other stored sensor DTCs. Is a sensor DTC stored? If yes, go to next step. If no, go to step  4 .
  3. Perform the other sensor DTC diagnosis before attempting diagnosis of this DTC. After repairs, go to step  10 .
  4. Perform a visual/physical inspection for the following conditions:
    • Any intake air duct leaks.
    • Any collapsed or damaged intake air ducts.
    • Any intake manifold and throttle body vacuum leaks.
    • An improperly installed or leaking fuel mixer.
    • Any debris near the MAF sensor inlet screen or damage to the inlet screen.
    • An improperly installed MAF sensor. Inspect the flow arrow for proper sensor installation.
    • Any Positive Crankcase Ventilation (PCV) system leaks, such as a loose or missing oil fill cap, an in-correct PCV valve, or faulty operation.

    Repair any condition as necessary. Was a repair made? If yes, go to step  10 . If no, go to next step.

  5. Perform the MAP Sensor Performance DTC diagnosis and return to this step. See DTC P0106: MAP/TP SENSOR PERFORMANCE/RANGE  . Was a MAP sensor fault present and repaired? If yes, go to step  10 . If no, go to next step.
  6. Perform the TP Sensor Performance DTC diagnosis and return to this step. See DTC P0121: TP SENSOR ANGLE OUT OF RANGE  . Was a TP sensor fault present and repaired? If yes, go to step  10 . If no, go to next step.
  7. Using the scan tool, clear the DTCs. Start the engine. View the captured data Freeze Frame Records for this DTC that was stored in step  2 . Observe the data parameters that give an indication of how the vehicle was being operated when this DTC set. Select DTC and the Specific DTC function. Enter the DTC number that was set. Operate the vehicle, within the Conditions For Setting DTC and the parameters observed when the DTC set, until the scan tool indicates the diagnostic ran. Does the scan tool indicate the diagnostic passed? If yes, go to next step. If no, go to step  9 .
  8. The fault is not present. Are any DTCs stored that have not been diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no, problem is intermittent. See INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  9. Replace the MAF sensor. See MASS AIR FLOW SENSOR under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - CHEVY EXPRESS & SAVANA - GASOLINE. After repairs, go to next step.
  10. Using the scan tool, clear the DTCs. Start the engine. View the captured data Freeze Frame Records for this DTC that was stored in step  2 . Observe the data parameters that give an indication of how the vehicle was being operated when this DTC set. Select DTC and the Specific DTC function. Enter the DTC number that was set. Operate the vehicle, within the Conditions For Setting DTC and the parameters observed when the DTC set, until the scan tool indicates the diagnostic ran. Does the scan tool indicate the diagnostic passed? If yes, system is okay. If no, go to step  2 .
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