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OBD-II · Engine and powertrain (P)

P1556

Manufacturer-specific code

Meaning by manufacturer

This code means different things on different makes. Find yours below.

  • Volkswagen, Audi, Seat, Skoda, Cupra

    Charge pressure control: negative deviation

    Actual boost is lower than requested (underboost). The engine computer may go into limp mode.

    Likely causes, most likely first

    1. 01Charge-air hose or intercooler leak
    2. 02Vacuum supply leak or faulty N75 boost-control valve on vacuum-operated systems
    3. 03Sticking turbo vanes, wastegate or actuator
    4. 04EGR valve stuck open
    5. 05Incorrect boost-pressure sensor reading
    6. 06Turbocharger wear or damage

    Severity: Caution: get it checked soon · DIY with tools and some experience