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

P25C1

Alternative Fuel Disable Signal Circuit

The feedback signal that confirms the alt-fuel disable command was carried out is missing or out of range. The fuel system cannot verify that the gas circuit is shut.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number5 / C1

Possible causes

  • Open feedback wire between relay and control module high
  • Feedback contact in the disable relay corroded or stuck medium

Inspection / repair

  • Difficulty: medium
  • DIY: shop recommended
  • Estimated cost: 120–600 €
  • Estimated time: 0.8–2.5 h
  • Component: alt fuel control module
  • Component: feedback sensor
  • 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