Circuit DescriptionThe coolant temperature sensor is a variable resistor sensor and is used to measure the temperature of the coolant of the engine. The engine control module (ECM) supplies 5 volts to the coolant temperature signal circuit. The ECM monitors the change in voltage caused by changes in the resistance of the sensor to determine the coolant temperature.

Component LocationThe engine coolant temperature sensor is located on the thermostat housing.

Conditions for Running the DiagnosticsThis diagnostic runs continuously when the engine is running.

Conditions for Setting the Fault CodesThe Engine Control Module (ECM) detected the engine coolant temperature was above a threshold and closed the EGR valve to reduce the engine coolant temperature.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.Exhaust Gas Recirculation (EGR) valve operation will be disabled.Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.Conditions for Clearing the Fault CodeTo validate the repair, perform a key cycle, and leave the key in the ON position for 1 minute.The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop TalkWhen the engine coolant temperature nears the engine protection limits, the EGR valve will be closed to reduce the coolant temperature. This fault code is used as an information fault code, only indicating that the EGR valve has closed. No malfunction has occurred to cause this fault code. Other engine protection fault codes will be active if the engine coolant temperature has exceeded the engine protection limits.

Possible Cause:1) ECM calibration