P25C3
Alternative Fuel Disable Signal Circuit Low
The disable feedback signal sits below its valid window. Usually a short to ground or an open pull-up that lets the input float low.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Feedback wire shorted to groundCommon
- Open pull-up resistor in the controller inputLess likely
- Connector pins corroded - high contact resistanceLess likely
Parts involved
- Alt Fuel Control Module
- Wiring Harness
P25C3 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.