You can check whether the sealing ring at the inlet valve port is invalid, or in other words: see whether the sealing ring is installed properly, whether it is hardened, and handle it accordingly after inspection. If the stool sensor is used for a long time, there may be impurities blocking the diaphragm of the solenoid valve, so that the diaphragm can not switch normally, this problem is more common.
The reason for the constant flow is that the solenoid valve is broken.
If the toilet induction flushing valve is long running water, it must be too much scale inside it, and the closure is not strict.