PACCAR PX-9 CM2350 (2013-17) Fault Code:3423 PID: SPN:4344 FMI:4 Aftertreatment Diesel Exhaust Fluid Line Heater 3 Circuit – Voltage Below Normal or Shorted to Low Source

Reason:
Aftertreatment Diesel Exhaust Fluid Line Heater 3 Circuit – Voltage below normal, or shorted to low source. Low signal voltage detected at the diesel exhaust fluid line heater 3 circuit.

Effect:
Possible reduced engine performance.

Circuit Description:
The aftertreatment diesel exhaust fluid line heaters are used to defrost and/or prevent freezing of the diesel exhaust fluid lines.

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 when the keyswitch is in the ON position and line heating is commanded ON.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the line heater voltage was below a calibratible value and the line heater current was below a calibratable valure.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.
2) The line heater will be disabled.
3) Diesel exhaust fluid injection into the aftertreatment system is disabled.
4) 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:
1) To validate the repair, perform a key cycle, and then use INSITE™ electronic service tool to perform the Diesel Exhaust Fluid Doser System Heater Test found under ECM Diagnostic Tests.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
4) 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.
5) The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
N/A

Possible Causes:
1) A malfunctioning line heater
2) A short circuit to ground in the OEM harness