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

P0235

Turbocharger/Supercharger Boost Sensor "A" Circuit

The ECU detected an electrical fault in the primary (A) boost pressure sensor circuit. The signal does not match plausibility checks against MAP, RPM, and load. With no boost feedback, the ECU typically limits boost via the wastegate.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number2 / 35

Possible causes

  • Boost pressure sensor failed high
  • Wiring or connector fault medium

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: possible
  • Estimated cost: 80–400 €
  • Estimated time: 0.3–2 h
  • Component: boost pressure sensor
  • Component: boost sensor wiring
  • Component: turbocharger
  • MIL / check engine light
  • emissions-relevant
  • limp mode possible

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