Cummins ISB4.5 CM2150 Fault Code: 3425 PID: SID 254 SPN: 4344 FMI: 5 Aftertreatment Diesel Exhaust Fluid Line Heater 3 Circuit – Current Below Normal or Open Circuit.

Posted by PerDiezel Solutions on January 21, 2026

Circuit Description
The aftertreatment diesel exhaust fluid line heater 3 is controlled by the aftertreatment diesel exhaust fluid controller, and receives power through the switch side of the diesel exhaust fluid line heater relay.

Component Location
The aftertreatment diesel exhaust fluid line heater 3 is located on the suction line between the diesel exhaust fluid tank and diesel exhaust fluid dosing unit.

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

Conditions for Setting the Fault Codes
The aftertreatment diesel exhaust fluid controller detects that the line heater circuit is open or shorted to ground.

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
-Upon completion of the repair, the heater must be commanded on for the diagnostic to run and the fault to go inactive.
-Use the INSITE™ electronic service tool to perform the “Diesel Exhaust Fluid Doser System Heater Test” found under “ECM Diagnostic Tests”.
-The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
-The ECM will turn off the MIL after three consecutive ignition cycles that the diagnostic runs and passes.
-This fault code and MIL can also be cleared with INSITE™ electronic service tool.

Possible Causes
-Malfunctioning line heater relay
-Malfunctioning line heater
-Open circuit, short circuit to ground, or a blown fuse in the aftertreatment diesel exhaust fluid controller harness
-Malfunctioning aftertreatment diesel exhaust fluid controller.

Cummins ISB4.5 CM2150 Fault Code: 3422 PID: SPN: 4344 FMI: 3 Aftertreatment Diesel Exhaust Fluid Line Heater 3 Circuit – Voltage Above Normal or Shorted to High Source.

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WARNING!