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Our automotive experts have put together the following information about the P257B 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 P257B code.

OBD II Fault Code

  • OBD II P257B

    OBD-II Code Climate control systems will not work is defined as a Vacuum Reservoir Control Circuit Low

    Diesel vehicles have a separate vacuum pump an reservoir because they cannot utilize vacuum from the engine the way a gasoline vehicles can. The engine control module (PCM) tells the vacuum pump when to turn on an off. If the PCM cannot control the pump, it will set code P257B.

    Climate control systems will not work Symptoms

    • Climate control systems will not work

    Common Problems That Trigger the P257B Code

    • Damaged vacuum reservoir
    • Powertrain Control Module (PCM) failure
    • Wiring issue
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