LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Kia >> 2017 >> Optima Plug-In Hybrid EX >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Diagnosis (1 Of 3) (PHEV) >> DTC P0091-00: Fuel Pressure Regulator 1 Control Circuit Low >> Component Inspection >> Fuel Pressure Regulator Inspection
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Fuel Pressure Regulator Inspection

  1. Ignition "OFF"
  2. Connect VMI to KDS/GDS and set up an oscilloscope as follow (4-channel);

    Channel A (+): Pin No. 1 (High) terminal of Fuel Pressure Regulator.

    Channel A (-): Pin No. 2 (Low) terminal of Fuel Pressure Regulator.

    Channel B (+): Pin No. 10 (Signal) terminal of Fuel Rail Pressure Sensor joint connector.

  3. Ignition "ON" & Engine "ON"
  4. Testing Condition: Idle & Approx. 4500 RPM

    Specification:  Refer to Figure below

    WARNING:
    G12367180Courtesy of KIA MOTORS AMERICA, INC.
  5. Is measured value within specification?

    YES 

    • Go to "Fuel Pressure Regulator Coil Resistance Inspection" procedure below.

    NO 

    • Carefully re-do this troubleshooting guide steps.
    • If no problems were found with the circuits or connectors, Replace the Fuel Pressure Regulator and then go to "VERIFICATION OF VEHICLE REPAIR " procedure.
    WARNING: In case of removing the high pressure fuel pump, high pressure fuel pipe, and injector, there may be injury caused by leakage of the high pressure fuel. So DO NOT perform any repair work right after engine is stopped.