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

P2595

Turbocharger Speed Sensor B Circuit Low

Turbo speed sensor B signal voltage below the lower limit — short to ground or open supply. Boost control tracks commanded vs. actual manifold pressure; persistent deviation means wastegate, vanes, hose or actuator are not delivering the requested pressure.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number5 / 95

Possible causes

  • Signal wire shorted to ground high
  • Connector pins corroded - high contact resistance low
  • Harness chafing through insulation low

Symptoms

  • Check engine light on
  • Significant power loss / limp mode
  • Possible blue or black smoke from exhaust
  • Whistling or hissing sound from intake

Inspection / repair

  • Difficulty: medium
  • DIY: shop recommended
  • Estimated cost: 200–1000 €
  • Estimated time: 0.6–2.5 h
  • Component: turbo speed sensor b
  • Component: sensor wiring
  • 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