Cummins X15 CM2350 X116B Performance Series (2018 & Newer) Fault Code: 6879 PID: SPN: 3246 FMI: 2/20 Aftertreatment 1 Diesel Particulate Filter Outlet Temperature Sensor – Data Not Rational – Drifted High

Lamp:
Amber

Reason:
An offset in the diesel particulate filter outlet temperature sensor reading has been detected.

Effect:
Possible reduced engine performance.

Circuit Description:
The aftertreatment diesel particulate filter temperature sensor module is a smart device that communicates with the engine control module via the J1939 data link. The aftertreatment diesel particulate filter temperature sensor module performs its own internal diagnostics and reports malfunctions back to the engine control module using the J1939 data link. The aftertreatment diesel particulate filter temperature sensor module is used to measure the aftertreatment diesel oxidation catalyst intake temperature, aftertreatment diesel particulate filter intake temperature, and aftertreatment diesel particulate filter outlet temperature. The temperature probes are permanently attached to the aftertreatment diesel particulate filter temperature sensor module and can not be replaced individually.

Component Location:
The aftertreatment diesel particulate filter outlet temperature sensor is located in the aftertreatment system. It is located at the outlet of the aftertreatment diesel particulate filter.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the keyswitch is in the ON position and the engine is running.

Conditions for Setting the Fault Code:
The Engine Control Module (ECM) detected the aftertreatment diesel particulate filter outlet temperature signal voltage was out of range high.

Action Taken When the Fault Code is Active:
1. The ECM illuminates the amber check engine lamp and/or malfunction indicator lamp (MIL) after the diagnostic fails on two consecutive trips.
2. A default value for the aftertreatment diesel particulate filter outlet temperature sensor reading is used.
3. Diesel exhaust fluid injection into the aftertreatment system is disabled.
4. 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 Code:
1. To validate the repair using a diagnostic road test, utilize a route that incorporates both stop and go city type driving and steady state highway type driving. It may be necessary to load the unit for certain diagnostics in the ECM to run.
2. To validate the repair using a chassis dynamometer, utilize a routine that incorporates acceleration and motoring events, steady state highway type operation, and load. This will simulate normal driving and allow the diagnostics in the ECM to run.
3. The fault code status displayed by the recommended diagnostic tool or equivalent will change to inactive immediately after the diagnostic runs and passes.
4. The ECM will turn off the amber check engine lamp immediately after the diagnostic runs and passes.
5. For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
6. The “reset all faults” command in the recommended diagnostic tool or equivalent can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
Possible causes of this fault code include:
1. A malfunctioning aftertreatment diesel particulate filter intake temperature sensor.
2. A malfunctioning aftertreatment diesel particulate filter outlet temperature sensor.
3. Build up or plugging on the inlet face of the diesel particulate filter.
4. Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.
5. For intermittent power supply and datalink communication issues with aftertreatment components, it is highly recommended that the OEM power distribution center fuses and relays be thoroughly checked for loose, missing or intermittent connections.