CM850 Electronic Control System – FAULT CODE 2976

Dosing Control Unit Temperature – Data Erratic, Intermittent, or Incorrect


Fault Code: 2976
SPN: 3361
FMI: 2
LAMP: Amber

Dosing Control Unit Temperature – Data Erratic, Intermittent, or Incorrect. An internal error has been detected in the catalyst dosing control unit.

Catalyst solution injection into the aftertreatment system is disabled.

Circuit: Dosing Control Unit.

Circuit Description

The dosing control unit communicates to the primary engine electronic control (ECM) through the J1939 data link network.

Component Location

The dosing control unit location is OEM dependent.

Shop Talk

Fault Code 2976 is triggered when the dosing control unit internal temperature sensor is reading a different value than the other temperature sensors on the engine. This indicates a problem with the internal temperature sensor of the dosing control unit. Dosing control unit electrical supply issues that cause the dosing control unit to remain powered when the key switch is turned OFF can cause Fault Code 2976 to become active.

On-Board Diagnostics (OBD) Information (Euro 4.5 Certified Engines):

  • The ECM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
  • An engine torque derate will be activated after 50 hours of engine operation with the fault code active.
  • To validate the repair and turn off the MIL, the engine must be shut down with the keyswitch in the OFF position for a minimum of 8 hours. After the 8 hour cold soak, if the ambient temperature is below 2°C [36°F] or above 25°C [77°F] start the engine and allow it to idle for 1 minute or run the diagnostic. If these temperatures can not be achieved, calibrate the EMC to the latest version found in the calibration revisions listed in the ECM Calibration Revision History.
  • The ECM turns OFF the MIL after 1 ignition cycle that the diagnostic runs and does not fail. The MIL lamp can not be cleared with INSITE™ electronic service tool. The fault code will be cleared from memory after 400 days or 9,600 hours of engine operation.

Refer to Troubleshooting Fault Code t05-2976

Last Modified:  08-Jul-2010