U0677Lost Communication With Fuel Level Sensor B
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- A second level sender is needed when a tank has two chambers, as in saddle tanks that straddle the driveshaft, or when a vehicle carries a second tank. GM's 25OBDG03B calls it sensor 2 of the secondary tank, used on vehicles with two senders and a mechanical transfer pump; its circuit checks fail below 10 % or above 60 % of the 5 V range in 40 of 50 samples (P2067/P2068, Type B). Ford's 2024 summary runs sender B through the same resistance, noise and stuck checks as A and adds P25B2 for a stuck reading on either. U0677 is the digital variant: sender B's messages stop arriving. No manufacturer documents it publicly. The gauge then misjudges the part of the tank sender B covers, and range and EVAP readiness suffer.
- What you may notice
- Gauge drops suddenly or never shows full
- Range estimate inaccurate
- Check engine light
- Likely causes
- LikelyWiring to the secondary-chamber sender damaged
- PossibleSender B electronics failed
- PossibleConnector at the secondary flange corroded
- RareReceiving module or software 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.