Cummins X12 CM2350 X119B (2018 & Newer) Fault Code: 7894 PID: SPN: 3246 FMI: 10/10 Aftertreatment 1 Diesel Particulate Filter Outlet Temperature – Abnormal Rate of Change

Lamp:
Amber

Reason:
The aftertreatment diesel particulate filter outlet temperature is not changing with engine operating conditions.

Effect:
Possible reduced engine performance.

Circuit Description:
The aftertreatment exhaust gas temperature sensor module is a smart device that communicates with the engine control module via the J1939 data link. The aftertreatment exhaust gas temperature sensor module performs its own internal diagnostics and reports malfunctions back to the engine control module using the J1939 data link. The aftertreatment exhaust gas temperature sensor module is used to measure the aftertreatment diesel oxidation catalyst intake temperature, aftertreatment diesel particulate filter intake temperature, aftertreatment diesel particulate filter outlet temperature, and aftertreatment SCR outlet temperature. The temperature probes are permanently attached to the aftertreatment exhaust gas 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 Diagnostic:
The engine must be turned OFF for period of 8 hours before this diagnostic will run. This diagnostic runs when the keyswitch is turned to the ON position after an 8 hour cold soak.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the aftertreatment diesel particulate filter outlet temperature sensor reading was higher or lower than the other temperature sensors on the engine after an extended period of engine off time.

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, the engine must be shut down with the keyswitch in the OFF position for 8 hours. After the 8 hour cold soak turn the keyswitch to the ON position for 30 seconds.
2. The fault code status displayed by the recommended diagnostic tool or equivalent will change to inactive immediately after the diagnostic runs and passes.
3. The ECM will turn off the amber check engine lamp immediately after the diagnostic runs and passes.
4. 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.
5. 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.