Circuit DescriptionThe high-pressure relief valve is a mechanical device that opens when the fuel pressure in the fuel rail exceeds a critical warning limit.

Component LocationThe high-pressure fuel pump is mounted to the gear housing. The fuel pump actuator is mounted on the fuel pump. The fuel pressure sensor is mounted in the high pressure fuel rail. The fuel pressure relief valve is mounted on the high pressure fuel rail.

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

Conditions for Setting the Fault CodesThe Engine Control Module (ECM) detected the fuel rail pressure had exceeded the fuel pressure relief valve limiting pressure, and the fuel pressure relief valve opened.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp and/or Malfunction Indicator Lamp (MIL) after the diagnostic fails on two consecutive trips.

Exhaust Gas Recirculation (EGR) valve operation will be disabled.Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.Conditions for Clearing the Fault CodeTo validate the repair, perform a key cycle, start the engine and run it at high idle for 5 minutes.

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.For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where 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 TalkPossible causes of this fault code include:

High fuel drain line restrictionA leaking or sticky fuel pump actuatorAir in the fuelA plugged fuel pump actuator mounting adapterThis fault indicates that the fuel rail pressure was high enough to open the fuel rail pressure relief valve.

Possible Cause:1) Rail Fuel pressure sensor failure2) Suction side fuel filters failure3) Fuel heaters valves are4) OEM fuel lines5) Fuel Tank Standpipes6) Fuel FIlter failure7) Fuel pump actuator failure8) ECM calibration