Cummins ISB4.5 CM2150 Fault Code: 3426 PID: SPN: 4346 FMI: 3 Aftertreatment Diesel Exhaust Fluid Line Heater 4 Circuit – Voltage Above Normal or Shorted to High Source.

Posted by PerDiezel Solutions on January 21, 2026

Circuit Description
The aftertreatment diesel exhaust fluid line heater 4 is powered and controlled by the aftertreatment diesel exhaust fluid controller.

Component Location
The aftertreatment diesel exhaust fluid line heater 4 is internal to the aftertreatment diesel exhaust fluid dosing unit and can not be serviced separately.

Conditions for Running the Diagnostics
This diagnostic runs when the keyswitch is in the ON position and the heater is commanded on.

Conditions for Setting the Fault Codes
The aftertreatment diesel exhaust fluid controller detects that the heater voltage is above a calibratible value.

Action Taken When the Fault Code is Active
-The electronic control module (ECM) illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.
– An engine torque derate will be activated
-The line heater will be disabled.

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. Perform a key cycle, and start the engine and let it idle for 1 minute.
-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 internal to the dosing unit
-Short circuit to battery in the aftertreatment diesel exhaust fluid controller harness
-Malfunctioning aftertreatment diesel exhaust fluid contoller.

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.

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.

Cummins ISB4.5 CM2150 Fault Code: 3418 PID: SPN: 191 FMI: 19 Transmission Output Shaft Speed – Received Network Data In Error.

Cummins ISB4.5 CM2150 Fault Code: 3383 PID: 411 SPN: 3058 FMI: 0 Engine Exhaust Gas Recirculation System – Data Valid But Above Normal Operating Range – Moderately Severe Level.

Cummins ISB4.5 CM2150 Fault Code: 3382 PID: SPN: 3058 FMI: 18 Engine Exhaust Gas Recirculation System – Data Valid But Below Normal Operating Range – Moderately Severe Level.

Cummins ISB4.5 CM2150 Fault Code: 3228 PID: SPN: 191 FMI: 9 Transmission Output Shaft Speed – Abnormal Update Rate.

WARNING!