Circuit DescriptionThe aftertreatment temperature sensors are used by the engine control module 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 engine control module provides a 5 volt reference voltage to the sensor. The engine control module monitors the change in signal voltage and converts this to a temperature value.

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

Component LocationThe aftertreatment diesel particulate filter intake temperature sensor is located in the aftertreatment system. It is located at the outlet of the diesel oxidation catalyst and before the diesel particulate filter. Reference the original equipment manufacturer service manual.

Conditions for Running the DiagnosticsThis diagnostic runs continuously when the engine is operating and active regeneration of the aftertreatment diesel particulate filter is occurring.

Conditions for Setting the Fault CodesThe engine control module detects that the aftertreatment diesel particulate filter intake temperature reading is greater than 800?C [1472?F] for more than 20 seconds, or the temperature differential across the diesel oxidation catalyst is greater than 500?C [932?F] for more than 120 seconds.

Action Taken When the Fault Code is ActiveThe engine control module illuminates the red STOP ENGINE lamp immediately when the diagnostic runs and fails.Active and stationary regeneration of the diesel particulate filter will be disabled.The EGR valve will be closed. Possible engine shutdown if the engine protection shutdown feature is enabled.Conditions for Clearing the Fault CodeTo validate the repair, start the engine and let it idle 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 engine control module will turn off the red STOP 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 TalkThis fault will go inactive immediately after the aftertreatment temperatures drop below the warning limit, and will likely be inactive when the vehicle is in the shop. For these reasons this troubleshooting tree must be used for both active and inactive fault codes.

Possible causes of this fault code include:

A malfunctioning fuel injector caused unburned fuel to enter the exhaust systemAftertreatment diesel particulate filter intake temperature sensor failed in-rangeExcessive engine oil introduced into the exhaust system from the engineEngine brake malfunctioned.Reference the appropriate original equipment manufacturer wiring diagram when troubleshooting circuits that utilize wiring supplied by the original equipment manufacturer.

For intermittent power supply and data link communication issues with aftertreatment components, it is highly recommended that the original equipment manufacturer power distribution center fuses and relays be thoroughly checked for loose, missing, or intermittent connections.

Possible Cause:1) ECM calibration