PACCAR MX (2004 Emissions) Fault Code: P229B Common Rail Pressure Release Valve Current – Too Low

Description

PACCAR MX (2004 Emissions) Fault Code: P229B Common Rail Pressure Release Valve Current – Too Low

SET CONDITIONS:
The PCI ECU (D420) detects that the measured common rail pressure release valve current is too low.

DIAGNOSTIC CONDITION:
This diagnostic runs continuously during starting and 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?
– No, repair successful
– Yes, repair unsuccessful

POSSIBLE CAUSES:
1. Faulty common rail pressure release valve wiring (open circuit)
2. Faulty common rail pressure release valve

ADDITIONAL INFORMATION:
1. The PCI ECU controls and checks the current of the common rail pressure release valve (L094). The current is controlled with a duty cycle.

2. When this DTC is active:
– the engine torque is reduced.
– the engine runs in protection mode.
– the rail pressure control is in the limp-home function.
– the rail pressure is limited to approximately 800 bar.