Cummins X15 CM2350 X116B Performance Series (2018 & Newer) Fault Code: 3866 PID: SPN: 3364 FMI: 1/1 Aftertreatment Diesel Exhaust Fluid Quality – Data Valid But Below Normal Operating Range – Most Severe Level

Lamp:
Amber

Reason:
The Diesel Exhaust Fluid (DEF) quality has been detected to be below a critical threshold.

Effect:
Possible reduced engine performance.

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 Control 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 aftertreatment diesel exhaust fluid tank level and tank temperature sensors. Location of the tank and sensor is OEM dependent.

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 Code:
The DEF quality sensor has detected that the DEF concentration has fallen below a critical threshold.

Action Taken When the Fault Code is Active:
1. The ECM illuminates the amber check engine lamp immediately when the diagnostic runs and fails.
2. Diesel exhaust fluid injection into the aftertreatment system is disabled.

Conditions for Clearing the Fault Code:
1. Start and idle the engine for 15 minutes.
2. The ECM will turn off the amber check engine lamp immediately after the diagnostic runs and passes.
3. The fault code status displayed by the recommended diagnostic tool or equivalent will change to inactive immediately after the diagnostic runs and passes.
4. 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. Degraded, diluted, or incorrect diesel exhaust fluid.
2. Malfunctioning aftertreatment DEF quality sensor.