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

P25FA

Turbocharger/Supercharger Bypass Valve C Control Circuit High

Voltage on the third bypass valve control line is above the expected window. Typical causes are a short to battery or an open solenoid coil.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number5 / FA

Possible causes

  • Control wire shorted to a B+ supply high
  • Open solenoid coil medium
  • Connector pins corroded - high contact resistance low

Symptoms

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

Inspection / repair

  • Difficulty: medium
  • DIY: shop recommended
  • Estimated cost: 120–900 €
  • Estimated time: 0.8–3 h
  • Component: bypass valve c
  • Component: bypass solenoid
  • Component: wiring harness
  • MIL / check engine light

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