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Home >> Buick >> 2015 >> Verano Leather >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 8 (Engine Controls And Fuel - 2.0L (LHU) - DTC P0010 To P0246) >> Diagnostic Information and Procedures >> DTC P0128: Engine Coolant Temperature (ECT) Below Thermostat Regulating Temperature >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different variant/trim than selected.
  1. Verify the DTC P00B7, P0116, P0117, P0118, P0597, P0598, or P0599 is not set.
    • If a DTC is not set 
  2. Verify the cooling system is filled to the correct coolant level. Refer to Cooling System Draining and Filling (2.4L LEA)Cooling System Draining and Filling (2.0L LHU) , and Loss of Coolant .
    • 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 79°C (174°F) when commanding the Engine Coolant Thermostat Heater to 0%.
    • If less than 79°C (174°F) 

      Replace the Engine Coolant Thermostat.

    • If greater than 79°C (174°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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