Paccar

PACCAR MX (2004 Emissions) Fault Code: P0072 Ambient Temperature – Voltage Too Low or Short Circuit to Ground on ECU (D420) Pin (C78)

SET CONDITIONS:
This DTC is set when the ECU detects a lower voltage than expected on the signal or control circuit of the ECU.

DIAGNOSTIC CONDITION:
The diagnostic runs continuously when the ignition is keyed on.

CORRESPONDING OBD READINESS MONITOR:
None

RESET CONDITION:
The DTC changes to inactive after the diagnostic runs and passes.

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 sensor or actuator signal wiring is interrupted.
2. The sensor or actuator signal wiring has a short circuit to ground.
3. A malfunction in the power supply of the sensor or actuator.
4. A malfunction of the sensor or actuator.

ADDITIONAL INFORMATION:
Multiple sensor related voltage-too-low DTCs can indicate a malfunction within a 5-V sensor power supply circuit of the PCI ECU.

PACCAR MX (2004 Emissions) Fault Code: P0073 Ambient Temperature – Voltage Too High or Short Circuit to Supply on ECU (D420) Pin (C78)

SET CONDITIONS:
This DTC is set when the ECU detects a higher voltage than expected on the signal or control circuit of the ECU.

DIAGNOSTIC CONDITION:
The diagnostic runs continuously when the ignition is keyed on.

CORRESPONDING OBD READINESS MONITOR:
None

RESET CONDITION:
The DTC changes to inactive after the diagnostic runs and passes.

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 sensor or actuator signal wiring has a short circuit to supply.
2. A malfunction of the sensor or actuator.

PACCAR MX (2004 Emissions) Fault Code: P0087 Fuel Pressure – Data Valid but Too Low, Most Severe

SET CONDITIONS:
The PCI ECU (D420) detects that the fuel pressure is too low for more than 5 seconds.

DIAGNOSTIC CONDITION:
This diagnostic runs when the engine has been running for more than 200 seconds.

CORRESPONDING OBD READINESS MONITOR:
None

RESET CONDITION:
1. This DTC changes to inactive when the fault is no longer detected.
2. This fault cannot be cleared from the ECU memory.

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. Faulty fuel pressure control valve
2. Restriction in the fuel supply or low performance of the fuel lift pump

ADDITIONAL INFORMATION:
1. The low-pressure fuel pressure is measured by the fuel pressure sensor (F801).
2. Engine torque is reduced when this DTC is active.

PACCAR MX (2004 Emissions) Fault Code: P0088 Fuel Pressure – Data Valid but Too High

SET CONDITIONS:
The PCI ECU (D420) detects that the fuel pressure is 14 bar [203 psi] or more for more than 10 seconds.

DIAGNOSTIC CONDITION:
This diagnostic runs when the engine has been running for more than 200 seconds.

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:
Shut-off valve in the fuel return pipe stuck in the closed position. Restriction in the fuel to tank return circuit or faulty fuel pressure control valve.

ADDITIONAL INFORMATION:
1. The low-pressure fuel pressure is measured by the fuel pressure sensor (F801).

2. Too high a pressure in the injector fuel return circuit can damage the electrical connectors of the injectors. Therefore, check the (white) connectors on the injectors for cracks if this DTC has been set.

PACCAR MX (2004 Emissions) Fault Code: P0093 Common Rail Fuel Pressure – Sudden Pressure Drop

SET CONDITIONS:
The PCI ECU (D420) detects that the actual rail pressure drops suddenly.

DIAGNOSTIC CONDITION:
This diagnostic runs when the rail pressure operating state is: Pump unit only.

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. An external or internal fuel leakage on the high pressure fuel system components (e.g., fuel injection pipe)
2. A faulty fuel injector

ADDITIONAL INFORMATION:
1. The rail pressure is closed-loop controlled. A comparison is made between the requested and actual rail pressure measured by the common rail pressure sensor.

2. The rail pressure is measured in the common rail by the common rail pressure sensor (F854).

3. When this DTC is active:
– The engine torque is reduced.
– The engine runs in protection mode.

PACCAR MX (2004 Emissions) Fault Code: P0094 Common Rail Pump Unit Control – Incorrect

SET CONDITIONS:
The PCI ECU (D420) detects that the common rail pump delivery (correction) is more than 25% for more than 4 seconds.

DIAGNOSTIC CONDITION:
This diagnostic runs when the rail pressure control state is: Pump unit only.

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. Only in case this DTC is set after a fuel injection pipe has been renewed; incorrect installation of the fuel injection pipe.
2. Air present in the fuel system. If the fuel system or parts of it have been emptied during maintenance or repair, this DTC may become active temporarily after the engine is started. If the DTC stays inactive when the engine is running, no further investigation is necessary.
3. Malfunction in the low-pressure fuel system
4. An external or internal leakage on the high-pressure fuel system components.
5. Common rail pump unit failure

ADDITIONAL INFORMATION:
1. The common rail pump units (L092 and L093) supply fuel to the common rail. The amount of fuel pumped to the rail (rail pressure) depends on the duration of the pump events of the pump units (pump delivery percentage).

2. The common rail pump unit control is closed-loop controlled. A comparison is made between the expected and the actual common rail pump unit activation duration.

3. When this DTC is active:
– The engine torque is reduced.
– The engine runs in protection mode.
– The maximum rail pressure is limited to 1300 bar.

PACCAR MX (2004 Emissions) Fault Code: P0095 Intercooler Temperature – Data Erratic, Intermittent or Incorrect

SET CONDITIONS:
The PCI ECU (D420) detects that the measured intercooler temperature sensor differs more than 3°C [5.4°F] from the average of other temperature sensor readings on the engine for more than 5 seconds (after the ignition has been keyed off for at least 8 hours).

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the ignition has been keyed off continuously for at least 8 hours
2. Difference between the coolant temperature and ambient temperature is less than 15°C [59°F]
3. Ambient temperature is more than -20°C [-4°F]

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? (Can be pending, inactive or active)
– No, repair successful
– Yes, repair unsuccessful

POSSIBLE CAUSES:
Intercooler temperature sensor deviation

ADDITIONAL INFORMATION:
For this diagnostic, the intercooler temperature sensor (F750) reading is compared with an average of other temperature sensor readings on the engine after the ignition has been keyed off for at least eight hours.

PACCAR MX (2004 Emissions) Fault Code: P0097 Intercooler Temperature – Voltage Too Low or Short Circuit to Ground on ECU (D420) Pin (C17)

SET CONDITIONS:
This DTC is set when the ECU detects a lower voltage than expected on the signal or control circuit of the ECU.

DIAGNOSTIC CONDITION:
The diagnostic runs continuously when the ignition is keyed on.

CORRESPONDING OBD READINESS MONITOR:
None

RESET CONDITION:
The DTC changes to inactive after the diagnostic runs and passes.

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 sensor or actuator signal wiring is interrupted.
2. The sensor or actuator signal wiring has a short circuit to ground.
3. A malfunction in the power supply of the sensor or actuator
4. A malfunction of the sensor or actuator

ADDITIONAL INFORMATION:
Multiple sensor related voltage-too-low DTCs can indicate a malfunction within a 5-V sensor power supply circuit of the PCI ECU.

PACCAR MX (2004 Emissions) Fault Code: P0098 Intercooler Temperature – Voltage Too High or Short Circuit to Supply on ECU (D420) Pin (C17)

SET CONDITIONS:
This DTC is set when the ECU detects a higher voltage than expected on the sensor signal input of the PCI ECU.

DIAGNOSTIC CONDITION:
The diagnostic runs continuously when the ignition is keyed on.

CORRESPONDING OBD READINESS MONITOR:
None

RESET CONDITION:
The DTC changes to inactive after the diagnostic runs and passes.

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 sensor signal wiring has a short circuit to supply.
2. A malfunction of the intercooler temperature sensor.