P2409Fuel Cap Sensor/Switch Circuit Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P2409 is the plausibility code of the fuel cap sensor family: the circuit is electrically sound, but the reported cap state does not fit other information. A switch that never changes over a refuelling event, or one that reports closed while the leak test sees a gross leak, would be typical cases. No manufacturer publicly documents P2409. The closest documented logic is pressure-based: Ford's OBD summary flags a loose or missing cap (P0457) when the tank fails to reach -8 inH2O of vacuum within 30 s after refuelling, and clears it once purge vacuum is back above that level. CARB requires input components to be checked for rationality as well as circuit faults. P2408 is the generic circuit fault, P2410/P2411 the low/high signal codes, P2412 a dropout.
- What you may notice
- Check engine light or fuel cap message although the cap is tight
- EVAP test results may be rejected
- Likely causes
- LikelyCap switch mechanically stuck in one position
- PossibleWrong or damaged cap that does not operate the sensor
- RareMisaligned filler door or neck after body repair
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €20 – €200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.