Cummins ISB4.5 CM2150 Fault Code: 1679 PID: SPN: 3031 FMI: 2 Aftertreatment Diesel Exhaust Fluid Tank Temperature – Data Erratic, Intermittent, or Incorrect.

Circuit Description
The aftertreatment diesel exhaust fluid temperature sensor is used by the electronic control module (ECM) to monitor the temperature of the aftertreatment diesel exhaust fluid inside the diesel exhaust fluid tank. The ECM monitors the voltage on the signal pin and converts this to a temperature value.

Component Location
The aftertreatment diesel exhaust fluid 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 for more information.

Conditions for Running the Diagnostics
This diagnostic runs at initial key on and continuously when the keyswitch is in the ON position.

Conditions for Setting the Fault Codes
The ECM detects that the aftertreatment diesel exhaust fluid tank temperature does not match the ambient temperature sensor reading at initial key-on, or the tank temperature does not increase after an extended period of engine operation.

Action Taken When the Fault Code is Active
-The ECM illuminates the amber CHECK ENGINE lamp and/or the MIL immediately after the diagnostic runs and fails.

Conditions for Clearing the Fault Code
-To validate the repair, start the engine and let it idle for 1 minute.
-The ECM will turn off the amber CHECK ENGINE light immediately after the diagnostic runs and passes.
-The ECM will turn off the MIL after 3 consecutive ignition cycles that the diagnostic runs and passes.
-This fault code and MIL can also be cleared with INSITE™ electronic service tool.

Possible Causes
-In-range malfunction of the diesel exhaust fluid tank temperature
-Damaged wiring harness
-Damaged aftertreatment diesel exhaust fluid controller