ISX12/ISX11.9 CM2250 Fault Code: 3429 | SPN: 4346 | FMI: 5Aftertreatment Diesel Exhaust Fluid Line Heater 4 Circuit – Current Below Normal or Open Circuit

Overview

Circuit Description

The aftertreatment diesel exhaust fluid dosing unit heater is used to defrost and/or prevent freezing of the diesel exhaust fluid dosing unit.

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 continuously when the keyswitch is in the ON position.

Conditions for Setting the Fault Codes

The Engine Control Module (ECM) detected an open in the line heater circuit.

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.

Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.

Conditions for Clearing the Fault Code

• To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
• The fault code status displayed by the recommended Cummins® electronic service tool or equivalent will change to INACTIVE immediately after the diagnostic runs and passes.
• The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
• For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
• The “Reset All Faults” command in the recommended Cummins® electronic service tool or equivalent can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk

Possible causes of this fault code include:

Malfunctioning line heater internal to the dosing unit.

Open circuit or short circuit to ground in the aftertreatment diesel exhaust fluid controller harness

Malfunctioning aftertreatment diesel exhaust fluid controller.

Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

For intermittent power supply and datalink communication issues with Aftertreatment Components, it is highly recommended that the OEM Power Distribution Center fuses and relays be thoroughly checked for loose, missing or intermittent connections.