U3549Hydrogen Tank High Pressure Sensor 1 Circuit
- Generic OBD-II code · Network
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- U3549 covers the electrical circuit of the high-pressure sensor that reads hydrogen pressure on the storage side, upstream of the regulator, where a full system holds up to 70 MPa, the ceiling set by FMVSS 308. Its value feeds the fuel gauge, fill logic and leak checks: a Hyundai patent watches it while the parked car briefly wakes, a GM patent trims it against the more precise low-pressure sensor whenever the regulator stands wide open, and Toyota compares the filling-side and supply-side sensors after refuelling. U3549 itself appears in no public manufacturer document. An open, a short or a signal outside its range leaves the gauge and leak monitoring blind; expect a warning and possibly limited power. The supply-line sensors have their own codes, U3564 and U3565.
- What you may notice
- Hydrogen system warning in the instrument cluster
- Fuel gauge or range display missing or implausible
- Fuel cell power limited
- Likely causes
- LikelyCorroded or damaged connector or wiring between sensor and storage controller
- PossibleHigh-pressure sensor faulty internally
- RareSensor supply voltage or ground missing
- RareHydrogen storage control unit faulty
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €150 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.