Cummins ISB CM850 (2003-06) Fault Code: 2772 PID: SPN: 3226 FMI: 15 Aftertreatment Outlet NOx – Data Valid But Above Normal Operational Range – Least Severe Level. The engine NOx output is higher than recommended levels.

On-Board Diagnostics (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)The ECM turns OFF the malfunction indicator lamp (MIL) after one ignition cycle that the diagnostic runs and does not fail. The MIL lamp and fault code can not be cleared using INSITE? electronic service tool.
3)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)Diesel exhaust fluid quality is not within specification
2)External leaks in the diesel exhaust fluid dosing unit and/or diesel exhaust fluid lines
3)Aftertreatment nozzle has malfunctioned
4)Aftertreatment diesel exhaust fluid dosing unit has malfunctioned or become damaged
5)Sulfur content of the diesel fuel is too high, fouling the selective catalytic reduction (SCR) catalyst and resulting in high NOx output
6)Aftertreatment nozzle is partially or completely plugged.

Possible repairs:

1)Replace the aftertreatment SCR catalyst.
2)Replace the aftertreatment nozzle.
3)Correct the OEM air supply connection or supply.
4)Replace the diesel exhaust fluid dosing unit.
5)Repair or replace diesel exhaust fluid lines and/or connectors.
6)Locate/remove source, inform OEM. If required replace components and connectors. Drain/refill the diesel exhaust fluid tank.
7)Replace the screen filter.
8)A damaged diesel exhaust fluid dosing unit has been detected. Replace the diesel exhaust fluid dosing unit.
9)If necessary, calibrate the ECM.