PACCAR MX (2004 Emissions) Fault Code: P1718 EGR Mass Flow – Data Valid but Too High

PACCAR MX (2004 Emissions) Fault Code: P1718 EGR Mass Flow – Data Valid but Too High

SET CONDITIONS:
The PCI ECU (D420) detects that the EGR mass flow is too high for more than 90 seconds.

DIAGNOSTIC CONDITION:
This diagnostic runs:
1. When the engine speed is between 1000 and 1900 rpm and
2. When the engine is running at a steady load and
3. The engine mode is SCR high-efficiency mode or standard mode and
4. The NOx sensor before catalyst (F844) is in the operating mode

CORRESPONDING OBD READINESS MONITOR:
EGR system monitor

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 following conditions:
– Corresponding readiness monitor displays ‘Ready’
– Diagnostic conditions are met
– Set conditions are met
3. Did the DTC come back?
– No, repair successful
– Yes, repair unsuccessful

POSSIBLE CAUSES:
1. EGR valve failure
2. NOx sensor before catalyst deviation

ADDITIONAL INFORMATION:
1. The engine NOx emission is, among others, controlled by varying the EGR flow toward the inlet manifold of the engine.
2. The engine NOx emissions are measured by the NOx sensor before catalyst (F844).