1. Magnets demagnetization: Magnets in the sensor will demagnetize with time, resulting in the sensor being unable to output pulse signals.

2. Inverted water meter: The water meter will be inverted under special use conditions. Once inverted, it will also generate pulse signals, and the cumulative measurement of this signal system is regarded as normal measurement.

3. Magnetic field interference: The pulse signal is subjected to electromagnetic interference during transmission, resulting in errors. Someone deliberately attached a magnet to the shell of the water meter to produce strong magnetic field interference, thus achieving the purpose of stealing water.

4. Mechanical vibration: The water meter itself is affected by external vibration or the vibration of water meter movement caused by "water hammer" in the water pipe will make the pulse sensor send out abnormal pulse signals, resulting in pulse error.

5. Signal interference: the pulse signal sent by the general water meter needs to be transmitted to the collector through the household line. If the transmission line quality is poor or the shielding effect is poor, external interference will cause system statistical error.