PACCAR PX-9 CM2350 (2013-17) Fault Code:3574 PID: SPN:4334 FMI:18 Aftertreatment 1 Diesel Exhaust Fluid Pressure – Data Valid But Below Normal Operating Range – Moderately Severe Level

Reason:
Aftertreatment Diesel Exhaust Fluid Pressure Sensor – Data Valid But Below Normal Operating Range – Moderately Severe Level. Low diesel exhaust fluid pressure has been detected in the dosing unit.

Effect:
Possible reduced engine performance.

Circuit Description:
The Engine Control Module (ECM) provides a 5 volt supply and a ground to the aftertreatment diesel exhaust fluid pressure sensor. The pressure sensor provides a signal to the ECM on the sensor signal circuit. This sensor signal voltage changes, based on the aftertreatment diesel exhaust fluid pressure supplied by the dosing unit. The ECM will detect a low signal voltage at low diesel exhaust fluid pressures, and a high signal voltage at high diesel exhaust fluid pressures.

Component Location:
The aftertreatment diesel exhaust fluid pressure sensor 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 diesel exhaust fluid dosing unit is in the priming or dosing state.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the aftertreatment diesel exhaust fluid pressure was less than a threshold.

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) Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.
3) Engine torque will be severely reduced.
4) Vehicle speed will be limited to 8 km [5 mi] per hour after extended engine operation with the fault code active.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform the “Aftertreatment Diesel Exhaust Fluid Doser Pump Override Test” found under “ECM Diagnostic Tests” in the INSITE™ electronic service tool
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:
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.

Troubleshoot other active SCR related faults before this fault.

Possible Causes:
1) Low diesel exhaust fluid tank level
2) Blocked, restricted, or frozen diesel exhaust fluid dosing unit supply line
3) Blocked or restricted diesel exhaust fluid tank filter
4) Blocked or restricted diesel exhaust fluid dosing unit filter
5) Blocked or restricted diesel exhaust fluid dosing unit supply line fitting
6) Malfunctioning diesel exhaust fluid dosing unit
7) Contaminated diesel exhaust fluid
8) Debris from the diesel exhaust fluid tank. If debris is found in the diesel exhaust fluid tank, clean the diesel exhaust fluid tank thoroughly and fill with certified diesel exhaust fluid.