PACCAR MX (2004 Emissions) Fault Code: P1088 Common Rail Fuel Pressure – Data Valid but Too High

PACCAR MX (2004 Emissions) Fault Code: P1088 Common Rail Fuel Pressure – Data Valid but Too High

SET CONDITIONS:
The PCI ECU (D420) detects that the measured rail pressure is more than 2840 bar [41191 psi].

DIAGNOSTIC CONDITION:
This diagnostic runs when the rail pressure operating state is: Release valve 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:
Common rail pressure release valve failure (stuck in the closed position)

ADDITIONAL INFORMATION:
1. This DTC becomes active in combination with other fuel system related DTCs. Troubleshoot these faults first.

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 engine mode: Protection.
– The engine runs in rail pressure control state: Release valve only.
– The maximum rail pressure is limited to 1300 bar.