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Home >> GMC >> 2014 >> Yukon SLT, 4WD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls/Fuel - 5.3L, 6.2L - DTC P0010 To DTC P0442 >> Diagnostic Information and Procedures >> DTC P0128 >> Circuit/System Verification

Circuit/System Verification

  1. Verify that DTC P0116, P0117, P0118, or P0119 is not set.

    If a DTC is set

  2. Verify the cooling system is filled to the correct coolant level. Refer to Cooling System Leak Testing , and Cooling System Draining and Filling (Static Fill) .
    • If the coolant level is not correct 

      Repair as necessary

    • If the coolant level is correct 
  3. Engine running for 15 min with the A/C OFF, increase the engine speed to 3,000 RPM.
  4. Verify the scan tool ECT Sensor parameter is greater than 80°C (176°F)
    • If less than 80°C (176°F) 

      Replace the Thermostat.

    • If greater than 80°C (176°F) 
  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

    • If the DTC does not set 
  7. All OK.
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