Cummins ISB CM850 (2003-06) Fault Code: 2773 PID: SPN: 3226 FMI: 0 Aftertreatment Outlet NOx – Data Valid but Above Normal Operational Range – Most Severe Level. The engine NOx output is higher than recommended levels.

On-Board Diagnostic (OBD) Information (Euro 4 Stage 1+ Certified Engines):

1)The ECM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2)An engine torque derate will be activated immediately after the fault code becomes active.
3)The ECM turns OFF the malfunction indicator lamp (MIL) after 1 ignition cycle that the diagnostic runs and does not fail. The MIL lamp and fault code cannot be cleared using INSITE? electronic service tool.
4)The fault code will be cleared from the memory after 400 days or 9600 hours of engine operation.

The NOx sensor is permanently attached to the NOx control module. They are serviced as a single component and can not be replaced individually.

Possible causes:

1)Catalyst solution quality is not within specification, catalyst solution pump and lines external leaks, catalyst solution injector plugged or restricted, and catalyst solution lines plugged or restricted. Catalyst dosing unit has malfunctioned or become damaged
2)Catalyst solution injector nozzle is partially or completely plugged.

Possible repairs:

1)Repair source or replace the aftertreatment SCR catalyst.
2)Clean or replace the aftertreatment nozzle.
3)Replace the DEF dosing unit.
4)Repair or replace DEF lines and/or connectors.
5)Replace the screen filter.
6)A damaged diesel exhaust fluid dosing unit has been detected. Replace the diesel exhaust fluid dosing unit.
7)If necessary, calibrate the ECM