Cummins X12 CM2350 X119B (2018 & Newer) Fault Code: 4243 PID: SPN: 3515 FMI: 10 Aftertreatment 1 Diesel Fluid Temperature 2- Abnormal Rate of Change

Circuit Description
The aftertreatment diesel exhaust fluid quality sensor is a smart device that communicates to the ECM via the J1939 datalink. The aftertreatment diesel exhaust fluid quality sensor performs its own internal diagnostics and reports malfunctions back to the primary engine contol module via the J1939 datalink. The aftertreatment diesel exhaust fluid quality sensor is used to measure the concentration of the aftertreatment diesel exhaust fluid in the tank.

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

Conditions for Running the Diagnostics
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 exhaust fluid tank temperature sensor reading was higher or lower than the other temperature sensors on the engine.

Action Taken When the Fault Code is Active
The ECM logs the fault code immediately when the diagnostic runs and fails.
Conditions for Clearing the Fault Code
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, start the engine and let it idle for 1 minute.
The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults.

Shop Talk
Possible causes of this fault code include:

Malfunctioning DEF Quality Sensor

Possible Cause:
1) Aftertreatment DEF tank temperature/quality sensor failure
2) ECM calibration