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Home >> Subaru >> 2022 >> WRX Base, Standard Trans >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (Diagnostics) (1 Of 4) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P0087: Fuel Rail/System Pressure - Too Low Bank 1 >> Notes

DTC P0087: Fuel Rail/System Pressure - Too Low Bank 1: Notes

1. - 

DTC detecting condition: 

Immediately at fault recognition

Trouble symptom: 

NOTE:

After the faulty parts are repaired or replaced, perform the final check in Basic Diagnostic Procedure. Ref. to  ENGINE (DIAGNOSTICS) (H4DOTC)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE 

  1. CHECK FOR FUEL DELIVERY LINE LEAKAGE  .

    Visually check the fuel delivery line for leakage.

    WARNING:
    • When checking fuel delivery line during engine operation, be very careful so that one's hair, body and clothes do not touch the rotating part in the engine compartment. 
    • If there is fuel leakage, the fuel can be combusted spontaneously by the engine heat, resulting in serious accident. Therefore, take extra care. 
    • Prepare the necessary fire-extinguishing appliance for immediate fire fighting in case of fire. 
    NOTE:

    Concerning the section where visible inspection is difficult, the fuel odor provides a good indication of determining the fuel leakage. 

    Are there leaks from the fuel delivery line?

    Yes  : Replace the faulty fuel delivery line.

    Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>FUEL DELIVERY AND EVAPORATION LINES

    Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>FUEL INJECTOR

    No  : Go to  2.

  2. CHECK DTC  .
    1. Turn the ignition switch to ON.
    2. Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Ref. to COMMON (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)

    Is DTC other than P0087 displayed? (Current code)

    Yes  : Check the appropriate DTC using the "Diagnostic Trouble Code (DTC)". Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST

    No  : Go to  3.

  3. CHECK EXPERIENCE OF RUNNING OUT OF FUEL  .

    Check if there was an experience of running out of fuel using Check List for Interview. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>CHECK LIST FOR INTERVIEW

    Has the vehicle experienced running out of fuel?

    Yes  : Finish the diagnosis.

    NOTE:

    DTC may be stored by running out of fuel. 

    No  : Go to  4.

  4. CHECK FUEL PRESSURE  .
    1. Start the engine.
    2. Using the Subaru Select Monitor, read the value of [Fuel Rail Pressure A] and [Commanded Fuel Rail Pressure A] when racing the engine.
      NOTE:

      For detailed operation procedures, refer to "COMMON (DIAGNOSTICS)". Ref. to  COMMON (DIAGNOSTICS)>DATA MONITOR 

    If the value of [Fuel Rail Pressure A] is synchronized with that of [Commanded Fuel Rail Pressure A], go to  A.

    If the value in [Fuel Rail Pressure A] does not increase, go to  B.

    If the value in [Fuel Rail Pressure A] does not change, go to  C.

    1. Go to  5.
    2. Go to  7.
    3. Replace the fuel pressure sensor. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>FUEL PRESSURE SENSOR
  5. CHECK OF FUEL PUMP  .
    1. Turn the ignition switch to ON. (Engine OFF)
    2. Using the Subaru Select Monitor, select [Fuel Pump Relay] of [Active Test].
      NOTE:

      For detailed operation procedures, refer to "Help" of application. 

    3. Check for operating sound in the fuel pump according to ON/OFF switching operation.

    Does the fuel pump emit operating sound?

    Yes  : Go to  6.

    No  : Check fuel pump circuit. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>DIAGNOSTICS WITH PHENOMENON>FUEL PUMP CIRCUIT

  6. CHECK FUEL PRESSURE  .

    Check the fuel pressure. Ref. to MECHANICAL (H4DOTC)>FUEL PRESSURE>INSPECTION

    Is the check result OK?

    Yes  : Go to  7.

    No  : Check the fuel pump and fuel delivery line.

    Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>FUEL PUMP ASSEMBLY>INSPECTION

    Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>FUEL DELIVERY AND EVAPORATION LINES>INSPECTION

  7. CHECK FOR FUEL DELIVERY LINE LEAKAGE (HIGH PRESSURE SIDE)  .
    1. Start the engine.
    2. Using the Subaru Select Monitor, read the change in values of [Fuel Rail Pressure A] when stopping the engine.
      NOTE:
      • In order to maintain the communication with Subaru Select Monitor, turn the ignition switch to OFF, and immediately turn it to ON. 
      • For detailed operation procedures, refer to "COMMON (DIAGNOSTICS)". Ref. to  COMMON (DIAGNOSTICS)>DATA MONITOR 

    Does the value of [Fuel Rail Pressure A] decrease rapidly?

    Yes  : Go to  8.

    No  : Go to  9.

  8. CHECK HIGH-PRESSURE FUEL PUMP  .

    Check the high-pressure fuel pump. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>HIGH PRESSURE FUEL PUMP>INSPECTION

    Is the check result OK?

    Yes  : Go to  9.

    No  : Replace the high-pressure fuel pump. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>HIGH PRESSURE FUEL PUMP

  9. CHECK FOR REPRODUCTION OF FAILURE  .
    1. Turn the ignition switch to ON.
    2. Using the Subaru Select Monitor or a general scan tool, perform the clear memory of [Engine]. Ref. to COMMON (DIAGNOSTICS)>CLEAR MEMORY
    3. Perform the corresponding inspection mode. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>INSPECTION MODE
    4. Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Ref. to COMMON (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)

    Is DTC P0087 displayed? (Current code)

    Yes  : Replace the high-pressure fuel pump. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>HIGH PRESSURE FUEL PUMP

    After replacement, go to the next step. Go to  10.

    NOTE:

    When the high-pressure fuel pump has been replaced in step 8, go to "CHECK FOR FUEL DELIVERY LINE LEAKAGE (HIGH PRESSURE SIDE)" without replacing the high-pressure fuel pump. Go to   11 . 

    No  : End.

  10. CHECK FOR REPRODUCTION OF FAILURE  .
    1. Using the Subaru Select Monitor or a general scan tool, perform the clear memory of [Engine]. Ref. to COMMON (DIAGNOSTICS)>CLEAR MEMORY
    2. Perform the corresponding inspection mode. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>INSPECTION MODE
    3. Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Ref. to COMMON (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)

    Is DTC P0087 displayed? (Current code)

    Yes  : Go to  11.

    No  : End.

  11. CHECK FOR FUEL DELIVERY LINE LEAKAGE (HIGH PRESSURE SIDE)  .
    1. Start the engine.
    2. Using the Subaru Select Monitor, read the change in values of [Fuel Rail Pressure A] when stopping the engine.
      NOTE:
      • In order to maintain the communication with Subaru Select Monitor, turn the ignition switch to OFF, and immediately turn it to ON. 
      • For detailed operation procedures, refer to "COMMON (DIAGNOSTICS)". Ref. to  COMMON (DIAGNOSTICS)>DATA MONITOR 

    Does the value of [Fuel Rail Pressure A] decrease rapidly?

    Yes  : Replace the fuel injector. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>FUEL INJECTOR

    No  : Repair the poor contact of ECM connector.

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