Circuit DescriptionThe engine control module (ECM) monitors engine operating conditions, including the reading of fuel rail pressure, and changes the flow command to either increase (OPEN the fuel pump actuator) or decrease (CLOSE the fuel pump actuator) the fuel supply to the high-pressure pump.

Component LocationThere are two fuel filters and several original equipment manufacturer (OEM) supplied components that can impact this fault code. The pressure-side fuel filter is typically mounted directly to the engine, but can also be remote mounted. The suction-side fuel filters and other OEM supplied components are OEM specific. The OEM is required to supply a suction-side filter, and the exact filter location is OEM dependent. Refer to the OEM service manual.

Conditions for Running the DiagnosticsThis diagnostic runs continuously when the engine is running.

Conditions for Setting the Fault CodesFuel pressure was less than a calibratible value during high fuel flow conditions indicating a fuel inlet restriction.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.Conditions for Clearing the Fault CodeTo validate the repair using a Diagnostic Road Test, utilize a route that incorporates both stop and go city type driving and steady state highway type driving. It may be necessary to load the unit for certain diagnostics in the ECM to run.To validate the repair using a Chassis Dynamometer, utilize a routine that incorporates acceleration and motoring events, steady state highway type operation, and load. This will simulate normal driving and allow the diagnostics in the ECM to run.The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop TalkLow fuel pressure at rated speed/load indicates a fuel inlet restriction or a plugged pressure-side fuel filter. Possible causes of this fault code include:

A plugged pressure or suction side fuel filterCollapsed fuel inlet linesAn obstructed suction tube in the fuel tankPlugged fuel tank vents.Malfunctioning high-pressure fuel systemNote: The mounting location of the suction side fuel filter will vary by OEM, and can possibly not be in an obvious location.

Possible Cause:1) Pressure-side fuel filter failure2) Suction-side fuel filter failure3) ECM calibration