PINPOINT TEST C : The Engine Does Not Reach Normal Operating Temperature: Notes

Normal Operation and Fault Conditions

The engine cooling system maintains engine temperature during operation. Correct coolant flow through the engine, radiator and remainder of cooling system passages and components is essential to maintaining a correct engine temperature.

Engine coolant flows primarily from the engine to the radiator circuit and back to the coolant pump. Coolant is sent from the coolant pump through the engine block and cylinder heads. A separate circuit from the engine also feeds the heater core with coolant. The coolant pump circulates the coolant. For 2.0L GTDI, the coolant pump is operated by engine rotation through the accessory drive belt pulley. For 3.5L Ti-VCT and 3.5L GTDI, the coolant pump is operated by engine rotation through the timing chain sprocket. The coolant thermostat is a control valve actuated by coolant temperature. When the thermostat is closed, coolant flow bypasses the radiator circuit and returns to the coolant pump. When the thermostat is opened, coolant flows through the radiator circuit in order to transfer engine generated heat to the outside air.

Concerns of engine inability to reach normal operating temperature typically occur when the rate of coolant flow through some coolant circuits (radiator, heater core) is more than expected given the conditions, or when the electric cooling fan operates all of the time. Heat is not allowed to build in the engine because a heat exchanger is removing too much heat, including the radiator, heater core and oil cooler. In addition, perceived concerns that the engine does not reach normal operating temperature can be related to a low coolant level or trapped air which does not allow for hot coolant to be available at the heater core, an inoperative climate control system, or for concerns perceived or related to an incorrect engine temperature gauge indication. The engine not reaching normal operating temperature can be attributed to:

Low coolant level
Thermostat
Engine cooling fan always on
Temperature gauge

Engine Cooling

DTC Fault Trigger Conditions

DTC	Description	Fault Trigger Conditions
P0125	Insufficient Coolant Temp for Closed Loop Fuel Control	Indicates the CHT sensor or ECT sensor has not achieved the required temperature level to enter closed loop operating conditions within a specified amount of time after starting the engine.
P0128	Coolant Thermostat (Coolant Temp Below Thermostat Regulating Temperature)	Indicates that the thermostat monitor has not achieved the required engine operating temperature within a specified amount of time after starting the engine.