PACCAR MX (2004 Emissions) Fault Code: U1579 BPV Actuator Position – Data Erratic, Intermittent, or Incorrect

PACCAR MX (2004 Emissions) Fault Code: U1579 BPV Actuator Position – Data Erratic, Intermittent, or Incorrect

SET CONDITIONS:
The PCI ECU (D420) receives a CAN message from the BPV valve actuator that contains an out-of-range value for the actuator shaft position.

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

CORRESPONDING OBD READINESS MONITOR:
None

RESET CONDITION:
This DTC changes to inactive after the ignition is keyed off for at least 15 seconds and keyed on again, and 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. This DTC can be a result of a BPV valve related P-code. Troubleshooting these P- codes first.
2. E-CAN communication
3. Faulty BPV valve actuator

ADDITIONAL INFORMATION:
1. The actuator of the BPV valve (L096) is a smart actuator that communicates with the PCI ECU via E-CAN. The actuator ECU is controlled by the PCI ECU but has its own diagnostics.
2. The position of the actuator shaft, and therefore the position of the BPV valve is monitored.