PACCAR MX (2004 Emissions) Fault Code: P1723 Exhaust Gas Pressure Before Turbine – Data Valid but Too Low

PACCAR MX (2004 Emissions) Fault Code: P1723 Exhaust Gas Pressure Before Turbine – Data Valid but Too Low

SET CONDITIONS:
The PCI ECU (D420) detects that measured pressure before turbine is lower than the requested pressure before turbine for more than 40 seconds.

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the engine speed is above 600 rpm and
2. When the engine is running at a steady load and
3. The [engine mode] is SCR HEATING, SCR HIGH EFFICIENCY, STANDARD or PROTECTION

CORRESPONDING OBD READINESS MONITOR:
None

RESET CONDITION:
This DTC changes to INACTIVE when the fault is no longer detected.

REPAIR VERIFICATION:
1. Clear all DTCs.
2. Test drive or operate the vehicle to meet the diagnostic conditions and set conditions.
3. Did the DTC come back?
– No, repair successful
– Yes, repair unsuccessful

POSSIBLE CAUSES:
1. The end-stops of the VTG turbocharger actuator programmed incorrectly

IMPORTANT: Turbocharger actuators are occasionally recalibrated by a technician in an attempt to solve VTG turbocharger actuator position-related DTCs. By doing so, the actuator is mistakenly calibrated to a smaller span than the initial maximum span of the turbocharger mechanism. In that case the requested pressure before turbine cannot be reached, resulting in DTC P1723.

2. Leaking exhaust system
3. Leaking pressure sensor before turbine tube
4. Plugged pressure sensor before turbine tube
5. Pressure sensor before turbine deviation

ADDITIONAL INFORMATION:
1. The PCI ECU uses the pressure before turbine for, among other things, controlling the VTG turbocharger, EGR valve position, BPV valve position and engine braking.

2. The pressure before turbine is measured by the pressure sensor before turbine (F826).