U3573Coolant Mixing Valve Control Circuit
- Generic OBD-II code · Network
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- U3573 concerns how the coolant mixing valve is powered: its actuator line may be interrupted or shorted, or the output stage may have failed. This three-way valve splits stack coolant between radiator and bypass and so decides how warm it is when it returns to the stack. Designs vary: in a Hyundai application a solenoid pushes a spool and its current sets the split, while Toyota describes a rotary valve turned by a stepper motor through a gear train. In the conventional Hyundai layout the valve takes the stack inlet temperature over CAN from the fuel cell control unit. If the actuator cannot be powered, coolant temperature is no longer regulated. U3573 appears in no public maker document. Likely consequences are a warning and capped output; how the valve itself responds is judged under U3574.
- What you may notice
- Fuel cell system warning, MIL on
- Stack temperature too high or too low, reduced power
- Slow warm-up of the fuel cell system
- Likely causes
- LikelyOpen, short or corrosion in wiring or connector of the valve actuator
- PossibleActuator motor or solenoid coil of the mixing valve faulty
- RareDriver stage or CAN link of the controlling unit faulty
- Repair
- Hard · Usually a job for a workshop.Typical cost: €200 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.