U3554Hydrogen Tank B Valve Enable Circuit
- Generic OBD-II code · Network
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- U3554 refers to the enable path that powers the tank B solenoid. Its purpose is a second, independent way to withdraw the permission for the valve to open. Toyota patented a layout in which the valve controller and the controller for high voltage sit at opposite ends of the car and back each other up: after a crash at one end, the controller at the undamaged end shuts the hydrogen valve. Toyota's FCHV guide also lists an opened hood or fuel door among the triggers that close the valves. A fault in such a release path keeps tank B shut even with an intact coil. No maker documents U3554 publicly. Check fuses, relays and the release wiring before the valve itself; U3553 covers the control side of the same valve.
- What you may notice
- Hydrogen system warning
- Range reduced or no READY
- Likely causes
- PossibleEnable relay or switch in the supply path faulty
- PossibleOpen or short in the enable line to valve B
- RareFaulty input that withdraws the release, such as a crash or flap signal
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €50 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.