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

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.