U0678Lost Communication With Fuel Level Sensor C
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- A third level sender only makes sense where the fuel volume is split further, for example a tank with three chambers or a main tank plus an auxiliary one. U0678 would be stored when such a sender C reports its value as a message and that message is lost. No manufacturer documents U0678 publicly, and the public OBD summaries checked here stop at two senders: GM's 2025 tables and Ford's 2024 summary, which covers A and B and a combined stuck code P25B2. The analog counterparts for C exist as P25D7 to P25DC. CARB lists stuck fuel level sensors among inputs that need extended monitoring, and the level enables EVAP tests, so a missing third reading keeps those monitors from running and leaves the gauge inaccurate.
- What you may notice
- Gauge or range wrong when the third chamber is involved
- Check engine light
- EVAP readiness not completed
- Likely causes
- LikelyWiring to sender C damaged or corroded
- PossibleSender C electronics failed
- RareModule receiving the level data faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €60 – €650
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.