PACCAR MX (2004 Emissions) Fault Code: P1866 Exhaust Gas Pressure Before Turbine – Data Valid but Too High

SET CONDITIONS:
The PCI ECU (D420) detects that the pressure before turbine is more than 9 bar.

DIAGNOSTIC CONDITION:
This diagnostic runs continuously when the engine is running.

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:
1. Clogging tube of the pressure sensor before turbine
2. Pressure sensor before turbine deviation
3. Malfunction of the VTG turbocharger or turbocharger actuator