Circuit DescriptionThe aftertreatment temperature sensors are used by the electronic control module (ECM) to monitor the engine exhaust temperatures in the aftertreatment system. The aftertreatment temperature sensors are thermistors and change resistance based on the temperature being measured. The ECM provides a 5 volt reference voltage to the sensor. The ECM monitors the change in signal voltage and converts this to a temperature value.

When the exhaust temperature is low, the sensor or thermistor resistance is high. The ECM signal voltage only pulls down a small amount through the sensor to ground. Therefore, the ECM senses a high signal voltage or a low temperature. When the exhaust gas temperature is high, the sensor resistance is low. The signal voltage pulls down a large amount. Therefore, the ECM senses a low signal voltage, or a high temperature.

Component LocationThe aftertreatment diesel oxidation catalyst intake temperature sensor is located in the aftertreatment system. It is located at the intake of the aftertreatment catalyst. Refer to the OEM service manual.

Conditions for Running the DiagnosticsThis diagnostic runs immediately after the engine has been started.

Conditions for Setting the Fault CodesThe diesel oxidation catalyst intake temperature is less than 150?C [302?F] for 5 minutes.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp and/or Malfunction Indicator Lamp (MIL) after the diagnostic fails on two consecutive trips.Conditions for Clearing the Fault CodeTo validate the repair, start the engine and let it idle for 5 minutes.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 after the diagnostic runs and passes.For On-Board Diagnostics (OBD) engines, the ECM will turn off the MIL after three consecutive trips where 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 TalkPossible causes of this fault code include:

A malfunctioning variable geometry turbocharger (VGT)An in-range malfunction of the aftertreatment diesel oxidation catalyst intake temperature sensorExhaust system leaks.

Possible Cause:1) Turbocharger failure2) VGT Actuator failure3) Charge-air cooler failure4) ECM calibration