U3563Cathode Bypass Valve Position Sensor Circuit
- Generic OBD-II code · Network
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- U3563 means the position sensor on the cathode bypass valve delivers no usable signal because of a broken wire, a short or a voltage outside its window. Toyota's patent mounts such a valve body position sensor right at the bypass valve, with pressure sensors before and after it; the angle tells the controller how the compressor air is really being split between stack and bypass. A Hydrogenics patent likewise fits angle sensors to the throttle-type valves of its stack. No public manufacturer source names U3563. Without the feedback, the controller has to infer the valve state indirectly, for example from compressor outlet pressure or stack current as Toyota describes, and will usually restrict operation. Drive faults of the valve are U3561, a mechanically misbehaving valve U3562.
- What you may notice
- Fuel cell system warning, MIL on
- Reduced power, especially at low load
- Likely causes
- LikelyOpen, short or moisture in the position sensor wiring or connector
- PossiblePosition sensor in the valve unit faulty
- RareShared 5 V supply or ground faulty (often with other sensor codes)
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €150 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.