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Home >> Chevrolet >> 2017 >> Spark LT, Automatic CVT Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 97 (Engine Controls And Fuel - 1.6L (LWC) - DTC P0010 To DTC P0238) >> Diagnostic Information and Procedures >> DTC P0128 >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different car, the 2019 Buick Cascada, 2018 Buick Cascada, and 2017 Buick Cascada. However, it is still accessible from the selected car via links, so may be relevant.
  1. Verify the condition does not exist:Incorrect fluid level or condition - Refer to:Loss of Coolant
    • If a condition exists 

      Repair or replace as necessary.

    • Go to next step: If no condition exists 
  2. Verify there are no DTCs set related to the following system/component:
    • B34 Engine Coolant Temperature Sensor
    • { If equipped }B203 Radiator Coolant Temperature Sensor
    • { If equipped }E41 Engine Coolant Thermostat Heater
    • { If equipped }Q74 Engine Coolant Bypass Valve
    • Go to next step: If a related DTC is not set 
  3. Perform the scan tool control function: Engine Coolant Thermostat Heater and Cooling Fan
    1. Engine Coolant Thermostat Heater - 100%
    2. Cooling Fan - 90%
    3. Engine Speed - 1, 800 to 2, 200 RPM
    • Verify the scan tool parameter: ECT Sensor = Less than 85°C (185°F) - Within 5 min
    • If 85°C (185°F) or warmer 

      Refer to: Circuit/System Testing

    • Go to next step: If colder than 85°C (185°F) 
  4. Perform the scan tool control function: Engine Coolant Thermostat Heater and Cooling Fan
    1. Engine Coolant Thermostat Heater - 0%
    2. Cooling Fan - 0%
    3. Engine Speed - 1, 800 to 2, 200 RPM
    • Verify the scan tool parameter: ECT Sensor = Greater than 102°C (215°F) - Within 5 min
    • If 102°C (215°F) or colder 

      Test or replace the component: E41 Engine Coolant Thermostat Heater

    • Go to next step: If warmer than 102°C (215°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.

    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 
  6. All OK.