P0091 - OBD II Trouble Code

Our automotive experts have put together the following information about the P0091 diagnostic trouble code. We've provided the common symptoms that occur when this code is set along with the frequent repairs that address the issues related to the P0091 code.

OBD II Fault Code

  • OBD II P0091

    OBD-II Code Decreased engine performance is defined as a Fuel Pressure Regulator 1 Control Circuit Low

    Diesel engines operate off of high fuel pressure. The engine computer (PCM) uses a Fuel Pressure Regulator to control the fuel on the low pressure side (from the fuel tank) to the high pressure injection pump (pressurizes the fuel to the injectors). If the PCM cannot control the fuel pressure regulator, code P0091 will set.

    Decreased engine performance Symptoms

    • Decreased engine performance
    • Increased fuel consumption

    Common Problems That Trigger the P0091 Code

    • Fuel pressure regulator failure
    • Powertrain Control Module (PCM) failure
    • Wiring issue

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