OBD-II code U3555 indicates a performance issue with the valve controlling hydrogen flow from Tank B in a hydrogen fuel cell vehicle. This means the powertrain control module has detected that the valve is not operating within its expected parameters, which can restrict hydrogen delivery to the fuel cell stack.
The valve itself may be mechanically stuck open or closed, or have an internal electrical failure preventing proper operation.
Corroded, damaged, or disconnected wiring and connectors to the Tank B valve can cause poor electrical contact or signal loss.
An inaccurate pressure sensor reading can cause the control module to incorrectly assess valve performance, triggering the code.
The dedicated controller for the fuel system may have failed internally, though this is much less common than a valve or wiring issue.
The main engine computer could be at fault, but this is extremely rare and should only be considered after all other possibilities are eliminated.
It depends on the severity. The vehicle may run normally using hydrogen from Tank A, but it may enter a reduced power mode or fail to start if the system shuts down as a safety precaution.
Hydrogen fuel cell vehicles typically use multiple tanks to store hydrogen gas. Tank B refers to one specific storage tank in this multi-tank arrangement.
Hydrogen vehicles have extensive safety redundancies. However, any fault with the high-pressure hydrogen system should be diagnosed by a qualified technician immediately to ensure system integrity.
No, replacing the PCM is almost never the correct fix for this code. The issue is almost always a failed valve, a wiring problem, or a sensor issue, and the PCM is mistakenly blamed.