Cummins ISB4.5 CM2150 Fault Code: 3868 PID: SPN: 3364 FMI: 9 Aftertreatment Diesel Exhaust Fluid Quality – Abnormal Update Rate.

Circuit Description
The DEF quality sensor is a smart device and communicates with the engine electronic control module (ECM) via the J1939 data link. The DEF quality sensor receives power and ground directly from the battery. The sensor performs its own internal diagnostics and reports malfunctions back to the primary engine ECM via the J1939 data link. The DEF quality sensor is used to measure the concentration of the DEF in the tank.

Component Location
The DEF quality sensor is typically mounted in the DEF dosing unit supply line. Reference the OEM service manual for a detailed component location view.

Conditions for Running the Diagnostics
This diagnostic runs continuously when they keyswitch is in the ON position.

Conditions for Setting the Fault Codes
This fault code is triggered when the ECM loses J1939 communications with the DEF quality sensor.

Action Taken When the Fault Code is Active
-The ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately after the diagnostic runs and fails.
-Engine torque will be reduced.

Conditions for Clearing the Fault Code
NOTE: This fault can not be cleared with INSITE™ electronic service tool.

-To validate the repair, start the engine and let it idle until the DEF system is thawed and primed.
-The ECM will turn off the amber CHECK ENGINE lamp and/or the MIL immediately after the diagnostic runs and passes.
-Use INSITE™ electronic service tool to verify that the fault code is inactive.
-The inactive fault code will be cleared from memory after 9,600 hours of engine operation without an occurrence again.