PACCAR MX (2004 Emissions) Fault Code: U1578 BPV Actuator Effort – Data Erratic, Intermittent, or Incorrect

Description

PACCAR MX (2004 Emissions) Fault Code: U1578 BPV Actuator Effort – 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 effort.

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 effort to move the actuator shaft is measured.