Some 2020-2025 Encore GX and 2021-2026 Trailblazer models equipped with the 1.3L engine (RPO L3T) may have an illuminated Check Engine MIL and DTCs P3075 (Engine Coolant Flow Too Low) and/or P0128 (Engine Coolant Temperature (ECT) Below Thermostat Regulating Temperature) or P1098 (Engine Oil Temperature Sensor 1 Circuit High Voltage) set due to failure of the Engine Coolant Flow Control Valve (CCV).
If these DTCs are set, inspect the CCV main rotary coolant valve (ball valve) using a borescope. (Fig. 9, #1) It should cycle smoothly.
Fig. 9
TIP: If DTC P3075 is the only DTC set, verify the coolant level at the radiator surge tank. If coolant level is low, refer to Loss of Coolant in the appropriate Service Information.
CCV Operation
The 1.3L engine features an active thermal management system with a water pump module that replaces the conventional mechanical water pump to manage engine oil temperature. The Coolant Control Valve assembly contains two rotary control valves. The block rotary coolant valve (Fig. 10, #1) and the main rotary coolant valve (Fig. 10, #2) both eliminate the need for the conventional cooling system thermostat. The engine oil cooler uses coolant to heat or cool the engine oil as required. The complete active thermal management system is controlled by the Engine Control Module (ECM).
Fig. 10
Inspect the CCV
To inspect the CCV, drain the cooling system and remove the intake air duct, air cleaner assembly and air cleaner outlet duct. Disengage the radiator inlet hose clamps at the CCV and radiator.
With a borescope in position to view the CCV ball valve, cycle the CCV from 0 degrees to 300 degrees using the Coolant Control Valve Actuator Special Function in GDS. (Fig. 11) If the CCV cycles smoothly, reprogram the Engine Control Module (ECM) using the latest calibrations available.
Fig. 11
If the CCV does not cycle or will not cycle smoothly, replace the CCV and reflash the ECM.
Refer to Engine Coolant Flow Control Valve Replacement L3T in the appropriate Service Information. After replacing the CCV, perform the CCV learn procedure and the Engine Coolant Pump data reset procedure.
For more details, including a video of the inspection and parts information, refer to Bulletin #26-NA-178.
– Thanks to Scott Willems
