P0088

CIRCUIT DESCRIPTION
The Engine Control Module (ECM) monitors Fuel Rail Pressure (FRP) using the fuel rail pressure sensor. If the sensor indicates a pressure more than the commanded rail pressure plus a possible transitional overshoot, The ECM will set Diagnostic Trouble Code (DTC) P0088 for fuel rail pressure too high.

CONDITIONS FOR RUNNING THE DTC
^ DTCs P0192, P0193, or P1635 are not set.
^ The ignition is ON.

CONDITIONS FOR SETTING THE DTC
The actual fuel pressure is more than 167 MPa.

ACTION TAKEN WHEN THE DTC SETS
^ The control module illuminates the Malfunction Indicator Lamp (MIL) when the diagnostic runs and fails.
^ The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
^ Use a scan tool in order to clear the MIL and the DTC.

DIAGNOSTIC AIDS
There are no driveability concerns associated with the fuel rail pressure regulator unless a DTC is present. The most likely cause of this DTC is a sticking fuel rail pressure regulator.

If the fuel system pressure is actually too high, a fuel knock and smoke condition will exist.

TEST DESCRIPTION

Steps 1-6:

The numbers below refer to the step numbers on the diagnostic table.
2. DTC P0090 is a current flow problem in the fuel rail pressure regulator circuit. This incorrect current draw could lead to incorrect fuel pressure. This hardware problem should be diagnosed before the performance DTC is checked.