OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Powertrain generic / SAE

P259F

Turbocharger A Boost Control Position At High Limit

The boost-control actuator on turbo A has been operating at the high end of its travel — the controller is saturated against the upper stop trying to bleed off boost. Indicates either a wastegate stuck closed, oversized turbo for the calibration, or commanded boost limits being exceeded by ambient conditions (cold dense air).

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number5 / 9F

Possible causes

  • Wastegate stuck closed high

Symptoms

  • Charge status indicator shows fault
  • Charging may not start or interrupts
  • Slower-than-expected charge rate

Inspection / repair

  • Difficulty: hard
  • DIY: shop recommended
  • Estimated cost: 200–2500 €
  • Estimated time: 0.8–5 h
  • Component: turbo actuator a
  • Component: wastegate
  • MIL / check engine light
  • emissions-relevant

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication