U0309Software Incompatibility With Alternative Fuel Control Module
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- An alternative fuel control module runs the gaseous fuel side of a bi-fuel or dedicated LPG or CNG engine and works alongside the gasoline or diesel controller. CARB counts such engines as alternate-fueled vehicles that fall under OBD II. U0309 is set when the partners find the module's software or calibration does not match theirs, for example after a conversion system or one of the controllers was updated on its own. Ford's 2014 code interpretation lists U0309 with the MIL marker. Roush CleanTech's propane systems for Ford E- and F-Series trucks show the arrangement: a smart relay module of the propane side talks to the Ford PCM and keeps its own fault list, including an internal software incompatibility code. U0108 means lost contact, U0409 invalid data. Expect a MIL and a fallback to the base fuel or rough running on gas.
- What you may notice
- Engine stays on or switches back to gasoline/diesel
- MIL and gas system warning on
- Rough running or hesitation in gas mode
- Likely causes
- LikelyGas system module software not released for the current engine controller calibration
- PossiblePCM/ECM reflashed by a dealer without updating the gas system module
- RareGas system module replaced with a unit of another variant
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €100 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.