Paccar

PACCAR MX (2004 Emissions) Fault Code: P1704 Lambda – Data Erratic, Intermittent or Incorrect, During Overrun

SET CONDITIONS:
The PCI ECU (D420) detects that the measured oxygen concentration in the exhaust differs too much from the expected oxygen concentration during coasting (fuel injection cutoff) for more than 2 seconds.

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the engine speed is above 1200 rpm and
2. During coasting (no fuel injection) and
3. When the coolant temperature is above 50°C [122°F] and
4. The lambda sensor (F834) is in the operating mode (if applicable).

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. Lambda sensor deviation (if equipped with lambda sensor)
2. NOx sensor before catalyst deviation (only if NOT equipped with lambda sensor)

ADDITIONAL INFORMATION:
IMPORTANT: Depending on the production date of the vehicle, either the lambda sensor (F834) or the NOx sensor before catalyst (F844) is used to determine the oxygen concentration in the exhaust gas.

1. Typically, high value air/fuel ratio indicates high oxygen concentration in the exhaust system.

2. When no combustion takes place, the oxygen concentration must be almost equal to the ambient air concentration (approximately 20%) after some time.

PACCAR MX (2004 Emissions) Fault Code: P1707 Lambda – Data Valid but Too Low

SET CONDITIONS:
The PCI ECU (D420) detects that the oxygen concentration measured by the lambda sensor is lower than the oxygen concentration measured by the NOx sensor before catalyst for more than 40 seconds.

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the engine speed is between 950 and 2000 rpm and
2. When the coolant temperature is above 50°C [122°F] and
3. The lambda sensor (F834) is in operating mode
4. The NOx sensor before catalyst (F844) is in operating mode
5. The engine mode is SCR high efficiency or standard or protection.

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

POSSIBLE CAUSES:
1. Lambda sensor deviation
2. NOx sensor before catalyst deviation

ADDITIONAL INFORMATION:
1. The PCI ECU uses the oxygen concentration in the exhaust measured by the lambda sensor (F834) to determine the air/fuel ratio of the combustion process.
2. The oxygen concentration in the exhaust measured by the lambda sensor is compared with the oxygen concentration measured by the NOx sensor before catalyst (F844).

PACCAR MX (2004 Emissions) Fault Code: P1708 Lambda – Data Valid but Too High

SET CONDITIONS:
The PCI ECU (D420) detects that the oxygen concentration measured by the lambda sensor is higher than the oxygen concentration measured by the NOx sensor before catalyst for more than 40 seconds.

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the engine speed is between 950 and 2000 rpm and
2. When the coolant temperature is above 50°C [122°F] and
3. The lambda sensor (F834) is in operating mode
4. The NOx sensor before catalyst (F844) is in operating mode
5. The engine mode is SCR high efficiency or standard or protection

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

POSSIBLE CAUSES:
1. Lambda sensor deviation
2. NOx sensor before catalyst deviation

ADDITIONAL INFORMATION:
1. The PCI ECU uses the oxygen concentration in the exhaust measured by the lambda sensor (F834) to determine the air/fuel ratio of the combustion process.

2. The oxygen concentration in the exhaust measured by the lambda sensor is compared with the oxygen concentration measured by the NOx sensor before catalyst (F844).

PACCAR MX (2004 Emissions) Fault Code: P1709 Lambda – Data Valid but Too Low During Overrun

SET CONDITIONS:
The PCI ECU (D420) detects that the measured oxygen concentration in the exhaust is too low while coasting (fuel injection cut off) 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 lambda sensor (F834) is in the operating mode (if applicable)

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. Lambda sensor deviation (if equipped with lambda sensor)
2. NOx sensor before catalyst deviation (only if NOT equipped with lambda sensor)

ADDITIONAL INFORMATION:
IMPORTANT: Depending on the production date of the vehicle, either the lambda sensor (F834) or the NOx sensor before catalyst (F844) is used to determine the oxygen concentration in the exhaust gas.

1. Typically, low air/fuel ratio indicates low oxygen concentration in the exhaust system.
2. When no combustion takes place, the oxygen concentration must be almost equal to the ambient air concentration (approximately 20%) after some time.

PACCAR MX (2004 Emissions) Fault Code: P170C NOx Sensor before Catalyst Response – Data Erratic, Intermittent or Incorrect, During Overrun

SET CONDITIONS:
The PCI ECU (D420) detects that the measured engine NOx emissions differ too much from the expected engine NOx emissions after 3 seconds during coasting (fuel injection cutoff).

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the engine speed is above 1200 rpm and
2. During coasting (no fuel injection) and
3. When the coolant temperature is above 50°C [122°F] 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. Faulty fuel system
2. NOx sensor before catalyst deviation

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