U3557 code meaning
Hydrogen Tank C Valve Enable Circuit
Network system Generic code U35xx codes Check engine light
What U3557 means
U3557 is stored for a fault in the enable circuit of the tank C valve, the third tank of three-tank vehicles. Permission to open is not tied to driving alone: a Honda patent describes the cutoff valve being open with the ignition off, for example when the stack keeps operating after shutdown, so collision detection stays powered in that state and a cutoff relay can still close the valve. The enable path therefore has to work when the car is parked, and faults may surface after switch-off. FMVSS 307 asks for valve closure within 5 seconds of any crash. No manufacturer documents U3557. Expect tank C to stay shut, a warning and less range. If U3551 and U3554 are also stored, look for a supply common to all valves.
U3557 at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor0.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U3557
- Hydrogen system warning, possibly right after switch-off or at start
- Reduced range
Common causes of U3557
- PossibleCutoff or enable relay for valve C faulty
- PossibleFuse or common valve supply interrupted
- PossibleEnable line to tank C damaged
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
H2 tank c valve enableSafety circuit
What each part of U3557 means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 57 | The exact fault in that area. |
What to do next
- Note U3557 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 U3557
What does U3557 mean?
U3557 means "Hydrogen Tank C Valve Enable Circuit". U3557 is stored for a fault in the enable circuit of the tank C valve, the third tank of three-tank vehicles. It is a generic code, so it means the same on every make.
Is it safe to drive with U3557?
Drive gently and only to a workshop. With U3557 the car can go into limp mode (reduced power) to protect itself.
Will U3557 fail an emissions test?
U3557 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 U3557 to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will U3557 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.