Epc gives an alarm, which suddenly goes out when it is on, and reports to epc when it is lit. What caused it?

Check the throttle. Maybe the throttle is too dirty, or there is something wrong with the throttle assembly. So this EPC warning light is on. After cleaning the throttle, you need to use a special computer to learn the idle speed again, otherwise the idle speed will be high. If you change the throttle, you need computer learning.