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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different car >> Section 102 (Engine Controls And Fuel - 6.0L (L96 LC8) - Diagnostic Information And Procedures (1 Of 2)) >> Diagnostic Information and Procedures >> DTC P0068 or P1101 >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition ON.
  2. Verify that DTC P0641, P0651, P0697, or P06A3 is not set.
    • Go to next step: If none of the DTCs are set 
  3. Verify the scan tool Throttle Body Idle Air Flow Compensation parameter is less than 90%.
    • Go to next step: If less than 90% 
  4. Verify the scan tool Throttle Position Sensors 1 and 2 Agree/Disagree parameter displays Agree while performing the Throttle Sweep Test with a scan tool.
    • Go to next step: If Agree 
  5. Determine the current vehicle testing altitude.
  6. Verify the scan tool MAP Sensor pressure parameter is within the range specified in the Altitude Versus Barometric Pressure table.
    • If the MAP Sensor parameter is not in range 

      Refer to DTC P0106  for further diagnosis.

    • Go to next step: If the MAP Sensor parameter is in range 
  7. Verify the scan tool MAF Sensor g/s parameter changes smoothly and gradually as the engine speed is increased and decreased while performing the actions listed below.
    1. Engine idling
    2. Perform the scan tool snapshot function.
    3. Increase the engine speed slowly to 3, 000 RPM and then back to idle.
    4. Exit from the scan tool snapshot and review the data.
    5. Observe the MAF Sensor parameter frame by frame with a scan tool.
    • The MAF Sensor parameter does not change smoothly and gradually 

      Refer to DTC P0101  for further diagnosis.

    • Go to next step: The MAF Sensor parameter changes smoothly and gradually 
  8. 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 data.
  9. Verify the DTC does not set.
    • If the DTC sets 

      Refer to Circuit/System Testing.

    • Go to next step: If the DTC does not set. 
  10. All OK.
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