PACCAR MX (2004 Emissions) Fault Code: P1408 Crankcase Air Pressure – Data Valid but Too High, Moderately Severe

SET CONDITIONS:
The PCI ECU (D420) detects that the measured crankcase pressure is too high for more than 10 seconds.

DIAGNOSTIC CONDITION:
This diagnostic runs continuously when the ignition is on.

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. Blocked or contaminated crankcase ventilation piping
2. Blocked or contaminated crankcase ventilation module

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