Overview

Code

Fault Code: 1679

PID: 

SPN: 3031

FMI: 2/2

LAMP: Amber

SRT:  

Reason

The diesel exhaust fluid tank temperature sensor has indicated a tank temperature too high or too low for the ambient conditions.

Effect

Possible reduced engine performance.

SAE J1939 Datalink

Circuit Description

The aftertreatment diesel exhaust fluid tank temperature sensor is used to monitor the temperature of the aftertreatment diesel exhaust fluid inside the aftertreatment diesel exhaust fluid tank.

Component Location

The aftertreatment diesel exhaust fluid tank temperature sensor is located in the diesel exhaust fluid tank. Location of the tank and temperature sensor is OEM dependent. Refer to the OEM service manual.

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 illuminates the amber CHECK ENGINE lamp and/or malfunction indicator lamp (MIL) after the diagnostic fails on two consecutive trips.

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 the recommended Cummins electronic service tool or equivalent 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.
• For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
• The “Reset All Faults” command in the recommended Cummins electronic service 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:

In-range failure of the diesel exhaust fluid tank temperature sensor

Damaged wiring harness

The type of diesel exhaust fluid tank temperature and level sensor used can vary depending on the vehicle OEM. As a result, the physical and/or electrical sensor configuration may vary slightly from what is shown in the troubleshooting and wiring diagram information.

Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

For intermittent power supply and datalink communication issues with Aftertreatment Components, it is highly recommended that the OEM Power Distribution Center fuses and relays be thoroughly checked for loose, missing or intermittent connections.

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