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

P25BF

Alternative Fuel Disable Control Circuit High

Voltage on the alternative-fuel disable control line is above the expected window. Often a short to battery upstream of the relay or a stuck-on driver in the control module.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number5 / BF

Possible causes

  • Disable control wire shorted to a B+ supply high
  • Output driver stuck on inside the control module medium
  • Connector pins corroded - high contact resistance low

Inspection / repair

  • Difficulty: medium
  • DIY: shop recommended
  • Estimated cost: 120–500 €
  • Estimated time: 0.8–2 h
  • Component: alt fuel control module
  • 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