U3550Hydrogen Tank A Valve Control Circuit
- Generic OBD-II code · Network
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- U3550 indicates an electrical fault in the control circuit of the solenoid valve on hydrogen tank A. This on-tank valve is the primary closure between tank and fuel system, and FMVSS 308 requires it to default to closed when unpowered. Toyota's FCHV guide lists when the controller shuts the valves of all tanks: vehicle off, abnormal pressure loss or rise, airbag or fuel cell crash sensors, a hydrogen sensor alarm, hood or fuel door opened, or a malfunction of a shut valve. An open coil, a short or a failed driver stage thus leaves tank A closed. No manufacturer documents U3550 publicly. With several tanks the others may keep the car moving with less range; the enable path is U3551, the mechanical function U3552.
- What you may notice
- Hydrogen system warning
- Reduced range, or no READY if the car depends on this tank
- Likely causes
- LikelyWiring or connector fault between controller and valve
- PossibleSolenoid coil of the tank A valve open or shorted
- RareValve driver stage in the storage control unit faulty
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €100 – €5,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.