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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different car >> Section 104 (Engine Controls And Fuel - 6.0L (L96 LC8) - Diagnostic Information And Procedures (2 Of 2)) >> Diagnostic Information and Procedures >> DTC P1111 or P1127 >> 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.
    NOTE:

    Verify that adequate fuel is in the fuel tanks before proceeding.

  1. If you were sent here from DTCs: P0111, P0112, P0113, or P0114, refer to Circuit/System Testing.
  2. Ignition ON, verify the IAT Sensor scan tool parameter is between -38 to +149°C (-36 to +300°F).
    • If not between -38 to +149°C (-36 to +300°F) 
    1. Ignition OFF, disconnect the X189 jumper harness male and female connectors from the components listed below.
      • B75B MAF/IAT sensor
      • Engine harness connector
    2. Connect the engine harness connector directly to the B75B MAF/IAT sensor, ignition ON.
    3. Verify the IAT Sensor scan tool parameter is between -38 to +149°C (-36 to +300°F).
    • Go to next step: If between -38 to +149°C (-36 to +300°F) 
  3. Engine idling for at least 2 minutes after the ECT scan tool parameter is at least 65°C (149°F).
  4. Verify the vehicle is operating in CNG mode.
    • If not in CNG mode 

      Refer to Circuit/System Testing.

    • Go to next step: If in CNG mode 
  5. 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.
  6. 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 
  7. All OK.
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