Cummins ISB4.5 CM2150 Fault Code: 3569 (Airless) PID: SPN: 3362 FMI: 7 Aftertreatment Diesel Exhaust Fluid Dosing Unit Input Lines – Mechanical System Not Responding or Out of Adjustment.

Posted by PerDiezel Solutions on January 20, 2026

Circuit Description
The diesel exhaust fluid dosing unit lines are responsible for transporting diesel exhaust fluid between the dosing unit, dosing valve, and diesel exhaust fluid tank.

Component Location
There are three diesel exhaust fluid lines. One line is between the dosing unit and dosing valve, 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 the aftertreatment architecture and OEM.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is in the ON position and dosing is being commanded.

Conditions for Setting the Fault Codes
The diesel exhaust fluid controller has detected a mechanical failure of the dosing input lines, and diesel exhaust fluid is not being delivered to the dosing valve.

Action Taken When the Fault Code is Active
-The ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.

Conditions for Clearing the Fault Code
-This fault code cannot be cleared with INSITE™ electronic service tool.
-To validate the repair, use INSITE™ electronic service tool to perform the “Diesel Exhaust Fluid Doser Override Test” under the “ECM Diagnostics Test” menu.
-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 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 able to build pressure, but could not complete the priming cycle. Troubleshoot all other active SCR related faults before this fault.

Possible Causes
-Blocked or restricted aftertreatment dosing valve.
-Blocked or restricted aftertreatment dosing valve supply line

Cummins ISB4.5 CM2150 Fault Code: 3569 PID: SPN: 3362 FMI: 7 Aftertreatment Diesel Exhaust Fluid Dosing Unit Lines – Mechanical System Not Responding or Out of Adjustment.

Cummins ISB4.5 CM2150 Fault Code: 3568 PID: SPN: 5394 FMI: 7 Aftertreatment Diesel Exhaust Fluid (DEF) Dosing Valve – Mechanical System Not Responding or Out of adjustment.

Cummins ISB4.5 CM2150 Fault Code: 3567 PID: SPN: 5394 FMI: 5 Aftertreatment Diesel Exhaust Fluid Dosing Valve – Current Below Normal or Open Circuit.

Cummins ISB4.5 CM2150 Fault Code: 3566 PID: SPN: 5394 FMI: 4 Aftertreatment Diesel Exhaust Fluid Dosing Valve – Voltage Below Normal or Shorted to Low Source.

Cummins ISB4.5 CM2150 Fault Code: 3565 PID: SPN: 5394 FMI: 3 Aftertreatment Diesel Exhaust Fluid Dosing Valve – Voltage Above Normal or Shorted to High Source.

Cummins ISB4.5 CM2150 Fault Code: 3564 PID: SPN: 5491 FMI: 5 Aftertreatment Diesel Exhaust Fluid Line Heater Relay – Current Below Normal or Open Circuit.

WARNING!