U3555Hydrogen Tank B Valve Performance
- Generic OBD-II code · Network
- Turns on the check-engine light
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- U3555 reports that the valve on tank B does not behave as expected although its circuit tests good. Leakage through the closed valve is one form. Hyundai patented a check for it while the car is parked: at wake-ups, hydrogen left in the supply line is fed into the stack with the tank valves shut, so the high-pressure reading should fall slightly; if it stays the same at each wake-up, the tank is feeding gas past the seal. The opposite is a valve that will not open. On the Nexo, venting for service closes the manual valve on each tank with a hex key, and a manual valve left shut afterwards would look like a stuck valve. No maker documents U3555. U3552 and U3558 are the siblings for A and C.
- What you may notice
- Hydrogen system warning, sometimes after parking
- Range lower than expected
- Likely causes
- PossibleTank B valve seat leaking when closed
- PossibleValve not opening mechanically
- RareManual tank valve not reopened after service
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €500 – €6,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.