Cummins X15 CM2450 X124B (2018 & Newer) Fault Code: 1685 PID: SPN: 3364 FMI: 4 Aftertreatment Diesel Exhaust Fluid Quality Sensor Circuit- Voltage Below Normal or Shorted to Low Source

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 aftertreatment diesel exhaust fluid quality sensor is located in the aftertreatment diesel exhaust fluid tank. It may be a combination sensor with the aftertreatement diesel exhaust fluid tank level and tank temperature sensors. Location of the tank and sensor is OEM dependent. Refer to the OEM service manual.

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

Conditions for Setting the Fault Codes
The Aftertreatment DEF quality sensor reported an out of range low condition.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.
Conditions for Clearing the Fault Code
To validate the repair, perform a key cycle, 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 ECM will turn off the amber CHECK ENGINE lamp 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 caused of this fault code include:

Malfunctioning DEF Quality Sensor

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