Paccar

PACCAR MX (2004 Emissions) Fault Code: P170E NOx Sensor Before Catalyst Response – Incorrect

SET CONDITIONS:
The PCI ECU (D420) detects that measured engine NOx emissions differ too much from the expected engine NOx emissions during transient operation of the engine (expected decrease of NOx emissions).

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the engine is running at a steady load and its speed is between 1200 and 1700 rpm and
2. The coolant temperature is above 50°C [122°F] and
3. The engine mode is DOC heating or DPF regeneration or SCR heating or SCR high efficiency or standard or protection and
4. The NOx sensor before catalyst (F844) is in the operating mode

CORRESPONDING OBD READINESS MONITOR:
Exhaust gas sensors 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:
NOx sensor before catalyst deviation

ADDITIONAL INFORMATION:
1. The measured engine NOx emissions are compared with the expected engine NOx emissions during transient operation of the engine.
2. The engine NOx emissions are measured by the NOx sensor before catalyst (F844).

PACCAR MX (2004 Emissions) Fault Code: P170F NOx Concentration Before Catalyst – Data Valid but Too High During Overrun

SET CONDITIONS:
The PCI ECU (D420) detects that the measured engine NOx emissions are too high for a fuel injection cutout situation for more than 21 seconds.

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. During coasting (no fuel injection) and
2. When the coolant temperature is above 50°C [122°F] and
3. The NOx sensor before catalyst (F844) is in the operating mode

CORRESPONDING OBD READINESS MONITOR:
Exhaust gas sensors monitor

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

IMPORTANT:
1. For Eaton Ultrashift transmissions, idle drop can only go to 1000 rpm.
2. For Alison Autoshift transmissions, it is not possible to conduct this test.

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:
NOx sensor before catalyst deviation

ADDITIONAL INFORMATION:
1. The measured engine NOx emissions are compared with the expected engine NOx emissions while coasting (fuel injection cutout).
2. The engine NOx emissions are measured by the NOx sensor before catalyst (F844).

PACCAR MX (2004 Emissions) Fault Code: P1710 NOx Concentration Before Catalyst – Data Valid but Too Low

SET CONDITIONS:
The PCI ECU (D420) detects that measured engine NOx emissions are lower than the expected engine NOx emissions for more than 40 seconds.

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the engine is running at a steady load and its speed is between 1050 and 1850 rpm and
2. When the coolant temperature is above 50°C [122°F] and
3. The engine mode is SCR high efficiency or standard or protection and
4. The NOx sensor before catalyst (F844) is in operating mode

CORRESPONDING OBD READINESS MONITOR:
Exhaust gas sensors 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. Humidity sensor deviation
2. NOx sensor before catalyst deviation

ADDITIONAL INFORMATION:
1. The measured engine NOx emission is compared with the expected engine NOx emission.
2. The engine NOx emissions are measured by the NOx sensor before catalyst (F844).

PACCAR MX (2004 Emissions) Fault Code: P1711 NOx Concentration Before Catalyst – Data Valid but Too High

SET CONDITIONS:
The PCI ECU (D420) detects that the measured engine NOx emissions are higher than the expected engine NOx emissions for more than 40 seconds.

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the engine is running at a steady load and its speed is between 1050 and 1850 rpm and
2. When the coolant temperature is above 50°C [122°F] and
3. The engine mode is SCR high efficiency or standard or protection and
4. The NOx sensor before catalyst (F844) is in the operating mode

CORRESPONDING OBD READINESS MONITOR:
Exhaust gas sensors 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 and a too high engine-out NOx level.

2. Diesel fuel used is not in accordance with EN590
3. Leakage in inlet air system
4. Clogged EGR pressure difference sensor venturi
5. Humidity sensor deviation
6. NOx sensor before catalyst deviation

ADDITIONAL INFORMATION:
1. The measured engine NOx emission is compared with the expected engine NOx emission.
2. The engine NOx emissions are measured by the NOx sensor before catalyst (F844).

PACCAR MX (2004 Emissions) Fault Code: P1718 EGR Mass Flow – Data Valid but Too High

SET CONDITIONS:
The PCI ECU (D420) detects that the EGR mass flow is too high for more than 90 seconds.

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?
– No, repair successful
– Yes, repair unsuccessful

POSSIBLE CAUSES:
1. EGR valve failure
2. NOx sensor before catalyst deviation

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).

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).

PACCAR MX (2004 Emissions) Fault Code: P171B EGR Flow Response – Decrease too Slow

SET CONDITIONS:
The PCI ECU (D420) detects that the EGR mass flow decrease is too slow during changes in the commanded EGR mass flow from a high to low rate.

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the engine speed is more than 1000 rpm and
2. The engine mode is DPF regeneration or SCR heating or SCR high efficiency or standard.

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. Clogged EGR system
2. Clogged EGR pressure difference sensor venturi
3. Sticking EGR 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. For this diagnostic, the EGR pressure difference sensor (F751) is used to measure the EGR mass flow during changes in the commanded EGR mass flow from a higher to lower flow rate.

PACCAR MX (2004 Emissions) Fault Code: P171C EGR Flow Response – Increase Too Slow

SET CONDITIONS:
The PCI ECU (D420) detects that the EGR mass flow increase is too slow during changes in the commanded EGR mass flow from a low to high rate.

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the engine speed is between 1000 and 1450 rpm and
2. The engine mode is DPF regeneration or SCR heating or SCR high efficiency or standard

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. Leaking EGR system
2. Clogged EGR system
3. Clogged EGR pressure difference sensor venturi
4. Sticking EGR 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. For this diagnostic, the EGR pressure difference sensor (F751) is used to measure the EGR mass flow during changes in the commanded EGR mass flow from a lower to higher flow rate.