PACCAR MX (2004 Emissions) Fault Code: P1719 EGR Mass Flow – Data Valid but Too Low

PACCAR MX (2004 Emissions) Fault Code: P1719 EGR Mass Flow – Data Valid but Too Low

SET CONDITIONS:
1. The PCI ECU (D420) detects that the EGR mass flow is too low for more than 90 seconds.
2. This DTC is set based on a one or two trip detection logic, depending on the PCI software version.

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the engine speed is between 1000 and 1900 rpm and
2. When the engine is running at a steady load and
3. The engine mode is SCR high-efficiency mode or standard mode and
4. The NOx sensor before catalyst (F844) is in the operating mode

CORRESPONDING OBD READINESS MONITOR:
EGR system monitor

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 following conditions:
– Corresponding readiness monitor displays ‘Ready’
– Diagnostic conditions are met
– Set conditions are met
3. Did the DTC come back? (Can be pending, inactive or active)
– No, repair successful
– Yes, repair unsuccessful

POSSIBLE CAUSES:
1. The end-stops of the VTG turbocharger actuator are not calibrated correctly

IMPORTANT: In an attempt the solve VTG turbocharger actuator position related DTCs, turbocharger actuators are occasionally recalibrated by a technician. 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 a too low flow of EGR gas.

2. Restricted air flow through intercooler/radiator. This can be caused by:
– A fouled bug screen
– A fouled intercooler
– The use of a winter front at temperatures above 4°C [40°F]
– The use of an aftermarket winter front with excessive airflow restriction through the
intercooler/radiator

3. Contaminated EGR cooler
4. Leaking EGR system
5. Leaking exhaust system between the cylinder head and turbocharger turbine
6. NOx sensor before catalyst deviation
7. Pressure sensor before turbine deviation
8. Plugged line to pressure sensor before turbine
9. Clogged EGR system (contaminated EGR cooler, contaminated EGR pressure difference sensor venturi)
10. Sticking EGR valve
11. Damaged EGR valve
12. Damaged BPV valve

ADDITIONAL INFORMATION:
1. The engine NOx emission is, among others, controlled by varying the EGR flow toward the inlet manifold of the engine.
2. The engine NOx emissions are measured by the NOx sensor before catalyst (F844).