U0670Lost Communication With Fuel Temperature Sensor A
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- GM's 2025 direct-injection engines measure fuel temperature in the high-pressure rail with digital SENT sensors, and sensor 1 is the one GM files under U0670. The test counts pulses on the signal wire: if the line sits permanently high and four or fewer pulses arrive (25OBDG03A; 40 or fewer in 25OBDG03B), a sample fails, and 400 bad samples in a window of 500, one every 6.25 ms, set the code; being Type A, it lights the MIL during the first trip. While it is active, GM holds back the range checks P0182/P0183 and the sensor comparison P111F. CARB requires a separate code when a digital input stops talking. The controller then substitutes a fuel temperature, so drivability rarely changes; the fault lies in wiring, connector or sensor.
- What you may notice
- Check engine light from the first trip
- Usually no noticeable change in driving
- Occasionally rougher hot restarts
- Likely causes
- LikelySENT signal wire to sensor A shorted or open
- PossibleConnector at the fuel rail loose or contaminated
- PossibleFuel temperature sensor A internally failed
- RareSENT receiver in the engine controller 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 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.