Cummins X15 CM2450 X124B (2018 & Newer) Fault Code: 6812 PID: SPN: 3515 FMI: 2/20 Aftertreatment 1 Diesel Exhaust Fluid Temperature 2 Sensor – Data Not Rational – Drifted High

Lamp:
None

Reason:
An offset in the diesel exhaust fluid quality sensor temperature reading has been detected.

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 DEF quality sensor is typically mounted in the DEF tank or in-line with the DEF dosing unit supply line.

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:
1. 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.
2. The fault code status displayed by the diagnostic tool will change to inactive immediately after the diagnostic runs and passes.
3. The reset all faults command in the diagnostic tool can be used to clear active and inactive faults.

Shop Talk:
Possible causes of this fault code include:
Malfunctioning aftertreatment DEF quality sensor.