Cummins ISB4.5 CM2150 Fault Code: 3575 PID: SPN: 4334 FMI: 16 Aftertreatment Diesel Exhaust Fluid Pressure Sensor – Data Valid but Above Normal Operating Range – Moderately Severe Level.

Circuit Description
The diesel exhaust fluid dosing unit returns diesel exhaust fluid to the tank through the return line.

Component Location
There are three diesel exhaust fluid lines. One line is between the dosing unit and aftertreatment nozzle, and the other two lines are between the dosing unit and diesel exhaust fluid tank. These lines can be partially hidden from view by the Selective Catalytic Reduction (SCR) system and other vehicle components. Line routing will vary, based on aftertreatment architecture and the OEM.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the engine is initially started and the SCR system is priming.

Conditions for Setting the Fault Codes
The diesel exhaust fluid dosing unit has detected a blockage in the return line (between the dosing unit and the tank).

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.
-Engine torque will be reduced.

Conditions for Clearing the Fault Code
-This fault code can not be cleared with INSITE™ electronic service tool.
-To validate the repair, it is necessary to start and idle the engine for up to 5 minutes to allow the diagnostic to run.
-Make sure that the diesel exhaust fluid dosing unit is able to successfully prime.
-The ECM will turn off the amber CHECK ENGINE lamp and/or MIL immediately after the diagnostic runs and passes.
-Use INSITE™ electronic service tool to verify that the fault code is inactive.
-The inactive fault code will be cleared from the memory after 9600 hours of engine operation without a reoccurrence.

Shop Talk
This fault indicates that the diesel exhaust fluid dosing unit was unable to return diesel exhaust fluid to the tank.

Possible Causes
-Blocked or restricted diesel exhaust fluid return line
-Malfunctioning diesel exhaust fluid dosing unit.

If diesel exhaust fluid lines blocked by buildup are detected, make sure that the dosing unit is purging correctly at key OFF. Incomplete purging of the dosing unit can also result in dosing unit damage caused by the freezing of the leftover diesel exhaust fluid in the system. Incomplete purge counts can be viewed using the Data Monitor/Logger menu in the aftertreatment section of INSITE™ electronic service tool. If the vehicle is equipped with a battery isolation switch, it must have a built-in delay device to prevent powering down of the dosing unit until the purge sequence is complete. If an OEM issue is identified as the cause of the malfunction, it must be documented and reported to the OEM as appropriate.