PACCAR MX (2004 Emissions) Fault Code: U17B5 Water in Fuel Drain Control – Current Too Low or Open Circuit on ECU (D420) Pin (A37)

SET CONDITIONS:
The PCI ECU detects an open circuit on pin A37.

DIAGNOSTIC CONDITION:
This diagnostic runs only 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. Interruption of the wiring on PCI ECU pin A37
2. Interruption of the wiring on PCI ECU pin A40
3. Faulty water drain valve

ADDITIONAL INFORMATION:
The water drain valve is combined with the water in fuel sensor and is installed on the fuel filtration module (L097).