PACCAR MX (2004 Emissions) Fault Code: P1407 Crankcase Air Pressure – Leakage Detected

PACCAR MX (2004 Emissions) Fault Code: P1407 Crankcase Air Pressure – Leakage Detected

SET CONDITIONS:
The PCI ECU (D420) detects that the measured crankcase pressure is too high for more than 30 seconds.

DIAGNOSTIC CONDITION:
This diagnostic runs 600 seconds after the engine has been started and when the coolant temperature is higher than 60?C [140?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:
1. Leakage on the crankcase ventilation pipe between the cylinder head cover and the crankcase ventilation module
2. Leakage on the crankcase pressure sensor bracket or pipe
3. Crankcase leakage (oil filler cap, dipstick)
4. Faulty crankcase ventilation module wiring
5. Faulty crankcase ventilation module
6. Valve seal(s) push up from valve guide(s)

ADDITIONAL INFORMATION:
The crankcase pressure is monitored with the crankcase pressure sensor (F806) against ambient pressure.