P0087

DTC P0087 Fuel Rail Pressure (FRP) Too Low

Circuit Description

The common rail fuel system is comprised of two fuel pressure sections: a suction side between the fuel tank and the fuel supply pump and a high-pressure side between the fuel supply pump and the fuel injectors. Fuel is drawn from the fuel tank via a feed pump and then pumped into the fuel rail by two plungers all of which are internal to the fuel supply pump. This high pressure is regulated by the ECM using the fuel rail pressure (FRP) regulator dependant upon values from the FRP sensor attached to the fuel rail. In case of fuel rail overpressure a pressure limiter valve threaded into the fuel rail will open to release overpressure and return fuel back to the fuel tank. If the ECM detects that the fuel rail pressure went excessively high then sharply decreased this DTC will set indicating high fuel pressure which activated the pressure limiter valve.

Condition for Running the DTC

^ DTCs P0091 P0092 P0192 P0193 P0642 and P0643 are not set.
^ The ignition switch is ON.

Condition for Setting the DTC

^ The ECM detects that the pressure limiter valve is activated with overpressure (more than 30,500 psi [210 MPa]) in the fuel rail.

Action Taken When the DTC Sets

^ The ECM illuminates the MIL when the diagnostic runs and fails. Refer to DTC Type Definitions for Action Taken When the DTC Sets - Type A.
^ The ECM limits fuel injection quantity.
^ The ECM inhibits EGR control.
^ The ECM inhibits DPF regeneration control.
^ The ECM inhibits cruise control.
^ The ECM inhibits PTO control.

Condition for Clearing the DTC

^ Refer to DTC Type Definitions for Condition for Clearing the MIL/DTC - Type A.

Diagnostic Aids

^ An intermittently sticking FRP regulator may have allowed the fuel pressure to become high enough to open the pressure limiter valve.
^ A skewed FRP sensor value can set this DTC. The FRP Sensor on the scan tool should read 0.9 to 1.0 volt after the engine has stopped running for a minimum of 30 seconds.

Important: If the fuel tank is empty or near empty, air might be allowed to go into the fuel system. With air in the fuel system, smooth flow of fuel into the supply pump is interrupted and this DTC may set. Perform bleeding of fuel system after refueling.

Test Description

The numbers below refers to the step number on the Circuit! System Testing.

7. This step checks for a fuel restriction by determining if a high vacuum is being pulled on the fuel system during normal operation.

8. This step checks for an air leak on the suction side of the fuel system by determining if a vacuum can be pulled when a fuel line is plugged.

Circuit System Testing DTC P0087