P25BE
Alternative Fuel Disable Control Circuit / Open
The controller cannot drive the alternative-fuel disable line that switches a bi-fuel vehicle (CNG, LPG, hydrogen) back to gasoline. An open detected on the control side blocks the safety shutoff for the gas system.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Broken wire or corroded connector on the disable control lineCommon
- Open coil in the alt-fuel disable relayPossible
- Output driver in the alt-fuel control module faultyLess likely
Parts involved
- Alt Fuel Control Module
- Alt Fuel Disable Relay
- Wiring Harness
P25BE 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.