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Aftertreatment Exhaust Gas Temperature 3 – Data Erratic, Intermittent, or Incorrect
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Overview
CODE | REASON | EFFECT |
Fault Code: 1878 PID: S328 SPN: 3245 FMI: 2/2 LAMP: Amber SRT: |
Aftertreatment Exhaust Gas Temperature 3 – Data Erratic, Intermittent, or Incorrect. The aftertreatment diesel particulate filter outlet temperature sensor is not changing with engine operating conditions. |
Active aftertreatment diesel particulate filter regeneration will be disabled. |
![]() ISX and ISM – Aftertreatment Temperature Sensors
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Circuit Description
The 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 voltage on the signal pin and converts this to a temperature value.
Component Location
The aftertreatment diesel particulate filter outlet temperature sensor is located in the aftertreatment system. It is located at the outlet of the diesel particulate filter. Refer to the OEM troubleshooting and repair manual.
Conditions for Running the Diagnostics
This diagnostic runs continuously when the engine is running and fuel injection into the aftertreatment system is not occurring.
Conditions for Setting the Fault Codes
- The ECM detects that the aftertreatment diesel particulate filter outlet temperature sensor reading is not changing with engine operating conditions.
Action Taken When the Fault Code is Active
- The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.
- A default value for the aftertreatment diesel particulate filter outlet temperature reading is used.
Conditions for Clearing the Fault Code
The ECM will turn off the amber CHECK ENGINE light immediately after the diagnostic runs and passes.
The engine must be running at 1200 RPM or above for 15 minutes and the aftertreatment diesel oxidation catalyst inlet temperature must be above 150°C [300°F] before the fault code will clear.
Shop Talk
Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe™ Online for applicable fixes to the calibration stored in the ECM. If necessary, recalibrate the ECM. Use the appropriate procedure in the corresponding Troubleshooting and Repair Manual for the engine being serviced. Refer to Procedure 019-032 in Section 19.
Possible causes of this fault code include:
- Stuck in-range aftertreatment diesel particulate filter outlet temperature sensor.
- High resistance in the aftertreatment diesel particulate filter outlet temperature sensor signal or return wires.
Refer to Troubleshooting Fault Code t05-1878