PACCAR MX (2004 Emissions) Fault Code: U1721 CAN – Message (VEP1) Time-Out from Aftertreatment System

PACCAR MX (2004 Emissions) Fault Code: U1721 CAN – Message (VEP1) Time-Out from Aftertreatment System

SET CONDITIONS:
This DTC is set when the repetition rate of the received CAN message is lower than expected or when the message is not received at all.

DIAGNOSTIC CONDITION:
The diagnostic runs continuously when the ignition is keyed on or when the engine is running.

CORRESPONDING OBD READINESS MONITOR:
None

RESET CONDITION:
The DTC changes to inactive after the diagnostic runs and passes.

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. Wiring issues (interruption or contact resistance)
2. Defective components
3. Incorrect software configuration