PACCAR MX (2004 Emissions) Fault Code: P1581 Turbo Speed – Data Valid but Too Low

PACCAR MX (2004 Emissions) Fault Code: P1581 Turbo Speed – Data Valid but Too Low

SET CONDITIONS:
The PCI ECU (D420) detects a too low value from the turbocharger speed sensor.

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the engine speed is above 1000 rpm and
2. The engine is loaded and
3. The VTG turbocharger position is less than 95%.

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. Exhaust gas leakage before the VTG turbocharger
2. Incorrectly fitted or loose turbocharger speed sensor (too large air gap)
3. Malfunction on the turbocharger speed sensor wiring
4. Malfunction on the turbocharger speed sensor
5. Restriction in exhaust or aftertreatment system

ADDITIONAL INFORMATION:
1. When P1581 is ACTIVE, the displayed turbo speed in the diagnostic service tool monitor is a calculated value based on a software model.
2. The turbo speed is measured by the turbocharger speed sensor (F683)
3. Engine torque is reduced when this DTC is active.