PACCAR MX (2004 Emissions) Fault Code: P1489 EGR Valve – Stuck Closed

PACCAR MX (2004 Emissions) Fault Code: P1489 EGR Valve – Stuck Closed

SET CONDITIONS:
The PCI ECU (D420) detects that the EGR valve is stuck closed since the EGR pressure difference is more than 0 bar [0 psi] and the EGR valve is commanded open.

DIAGNOSTIC CONDITION:
This diagnostic runs when the engine is running.

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. Loose actuator lever and/or connection rod
2. Sticking or blocked EGR valve or mechanism

ADDITIONAL INFORMATION:
1. The position of the actuator shaft, and therefore the position of the EGR valve, is monitored. Valve position: 0% is fully closed and 100% is fully open.
2. The engine NOx emission is, among others, controlled by varying the EGR gas mass flow toward the inlet manifold of the engine.
3. The EGR gas mass flow is calculated using the EGR pressure difference sensor (F751) and the EGR temperature sensor (F749).
4. EGR gas mass flow toward the inlet manifold of the engine is controlled by the EGR valve module (L095).

IMPORTANT: The EGR valve position is not the only parameter that is used to determine the amount of EGR gas flow.

The amount of EGR gas fed back to the inlet manifold mainly depends on the pressure difference between the pressure before turbine and the boost pressure, in combination with the EGR valve position.