PACCAR MX (2004 Emissions) Fault Code: P103C EGR Control – Unable to Reach Target

PACCAR MX (2004 Emissions) Fault Code: P103C EGR Control – Unable to Reach Target

SET CONDITIONS:
The PCI ECU (D420) detects that the demanded NOx conversion is limited by the EGR system limits for more than 300 seconds.

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the engine is running at a steady load and
2. Coolant temperature is above 50°C [122°F]

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? (Can be pending, inactive or active)
– No, repair successful
– Yes, repair unsuccessful

POSSIBLE CAUSES:
1. Leaking EGR system
2. Clogged EGR system
3. Clogged EGR pressure difference sensor venturi
4. NOx before catalyst sensor deviation

ADDITIONAL INFORMATION:
One way in which the engine NOx emission is controlled is by varying the EGR flow toward the inlet manifold of the engine.