P0088
DTC P0088 Fuel Rail Pressure (FRP) Too HighCircuit 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.
If the ECM detects that the fuel pressure went excessively high for a certain length of time this DTC will set (First Stage). If the ECM detects that during the same ignition cycle the fuel pressure rose even higher than the amount to set DTC P0088 fora certain length of time the MIL will be illuminated (Second Stage). If the MIL is illuminated the fuel pressure was too high and the pressure limiter valve did not active or did not active quick enough.
Condition for Running the DTC
First Stage Diagnosis:
^ DTCs P0091 P0092 P0192 P0193 P0642 and P0643 are not set.
^ The ignition switch is ON.
Second Stage Diagnosis:
^ DTCs P0091 P0092 P0192 P0193 P0642 and P0643 are not set.
^ The battery voltage is between 10 to 16 volts.
^ The ignition switch is ON.
Condition for Setting the DTC
First Stage Diagnosis:
^ The ECM detects that the actual fuel rail pressure is more than 26,800 psi (185 MPa) for longer than 10 seconds.
Second Stage Diagnosis:
^ The ECM detects that the actual fuel rail pressure is momentarily more than 33,400 psi (230 MPa) anytime during the ignition cycle after first stage has occurred. (This indicates the fuel rail pressure is too high and pressure limiter valve most likely did not active.)
Action Taken When the DTC Sets
First Stage Diagnosis:
^ The ECM will not illuminate the MIL or SVS lamp. Refer to DTC Type Definitions for Action Taken When the DTC Sets - Type D.
Second Stage Diagnosis:
^ 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
First Stage Diagnosis:
^ Refer to DTC Type Definitions for Condition for Clearing the DTC - Type D.
Second Stage Diagnosis:
^ 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 set this DTC.
^ Normal Actual Fuel Rail Pressure readings on the scan tool with the engine running in neutral at idle is around 3,900 to 4,800 psi (27 to 33 MPa) after warm up.
^ 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.
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 P0088
