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

The EGR temperature value is used by the ECM for the engine protection system and engine emissions control.

Component LocationThe EGR temperature sensor is located on the EGR connection tube between the EGR valve and the air intake connection.

Conditions for Running the DiagnosticsThis diagnostic runs continuously when the keyswitch is in the ON position.

Conditions for Setting the Fault CodesThe ECM detects that the EGR temperature is greater than 293?C [560?F] for more than 5 seconds.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.The engine torque will be derated up to 40 percent to limit the EGR temperature.Conditions for Clearing the Fault CodeTo validate the repair using a Diagnostic Road Test, utilize a route that incorporates both stop-and-go city driving and steady state highway driving. It may be necessary to load the unit for certain diagnostics in the ECM to run.To validate the repair using a Chassis Dynamometer Test, utilize a routine that incorporates acceleration and motoring events, steady state highway operation, and load. This will simulate normal driving and allow the diagnostics in the ECM to run.The fault code status displayed by INSITE? electronic service tool will change to INACTIVE immediately after the EGR temperature falls below 250?C [482?F] and the diagnostic runs and passes.The ECM will turn off the amber CHECK ENGINE lamp 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.

Shop TalkPossible causes of this fault code include:

A fouled EGR coolerPlugged or restricted EGR differential pressure sensor portsA damaged EGR valveA stuck open turbocharger control valveA low reading from the EGR differential pressure sensorA low reading for the EGR valve position sensorHigh exhaust temperaturesLow coolant levelHigh coolant temperatureAn incorrect coolant/water mixtureA stuck closed variable geometry turbocharger.NOTE: This fault code will most likely not be active with no load in the shop. The engine must be loaded to trigger this fault code.

Possible Cause:1) EGR temperature sensor failure2) EGR cooler3) ECM calibration