E4 appears because the pressure switch is out of order, which is easy to solve. First take out the inner container, then disassemble the bottom cover of the machine, and you can see the wiring layout below. The position marked with a red circle is the pressure switch. You can hear the snapping sound by pressing it lightly with your hand. Press it a few times more, and then blow it with a hair dryer (just cold air). Sometimes entering dirty things will also affect the work of the pressure switch. This is what I asked the customer service to answer. I did the same thing. The pot is back to normal)