High voltage is usually caused by the cooling fan not working, so you should check the safety and wiring of the fan. Under normal pressure, it is likely to be related to long-term use of tap water. Tap water is easy to form scale in engine cooling channels and pipes. Over time, due to the increase of scale, some pipes that are not often used will be blocked, and the heater test tube of this car is likely to be blocked. In addition, the water heater suddenly turns on, and the high water pressure will cause the aging water pipe to burst.