U3550 code meaning
Hydrogen Tank A Valve Control Circuit
Network system Generic code U35xx codes Check engine light
What U3550 means
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.
U3550 at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 8 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U3550
- Hydrogen system warning
- Reduced range, or no READY if the car depends on this tank
Common causes of U3550
- Most likelyWiring or connector fault between controller and valve
- PossibleSolenoid coil of the tank A valve open or shorted
- Less likelyValve driver stage in the storage control unit faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
H2 tank a valveValve wiring
What each part of U3550 means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 50 | The exact fault in that area. |
What to do next
- Note U3550 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U3550
What does U3550 mean?
U3550 means "Hydrogen Tank A Valve Control Circuit". U3550 indicates an electrical fault in the control circuit of the solenoid valve on hydrogen tank A. It is a generic code, so it means the same on every make.
Is it safe to drive with U3550?
Drive gently and only to a workshop. With U3550 the car can go into limp mode (reduced power) to protect itself.
Will U3550 fail an emissions test?
U3550 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U3550 to fix?
Difficulty: workshop only. A typical repair takes 1 to 8 hours of work. This is a job for a workshop.
Will U3550 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.