Cummins X15 CM2450 X124B (2018 & Newer) Fault Code: 6794 PID: SPN: 7854 FMI: 2/21 Aftertreatment 1 Particulate Sensor Module – Data Not Rational – Drifted Low

Lamp:
None

Reason:
An offset in the particulate matter sensor reading has been detected.

Effect:
Possible reduced engine performance.

The aftertreatment particulate matter sensor is a smart device and communicates with the Engine Control Module (ECM) via the J1939 data link.

Circuit Description:
The aftertreatment particulate matter sensor is a smart device and communicates with the Engine Control Module (ECM) via the J1939 data link. The aftertreatment particulate matter sensor performs internal diagnostics and reports malfunctions back to the primary ECM using the J1939 data link. The particulate matter sensor is permanently attached to the particulate matter control module. They are serviced as a single component and can not be replaced individually. The aftertreatment particulate matter sensor is used to measure the soot emissions at the outlet of the aftertreatment system.

Component Location:
The aftertreatment particulate matter sensor location can vary depending on engine application. It is usually located in the exhaust system at the outlet of the Selective Catalytic Reduction (SCR) catalyst.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the engine is running.

Conditions for Setting the Fault Codes:
The aftertreatement particulate matter sensor has detected the probe temperature value is not changing with conditions.

Action Taken When the Fault Code is Active:
The 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 Code:
1. Perform a key cycle.
2. Start and idle the engine.
3. To validate the repair, use the diagnostic tool to perform the “aftertreatment current based particulate matter sensor regeneration test” found in ECM diagnostic test.
4. The ECM will turn off the amber check engine lamp immediately after the diagnostic runs and passes.
5. The fault code status displayed by the diagnostic tool will change to inactive immediately after the diagnostic runs and passes.
6. 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.
7. The reset all faults command in the diagnostic tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
Possible causes for this fault include:
Malfunctioning aftertreatment particulate matter sensor.