My Diplomat dishwasher shows E5 what is wrong with it?

Hello, I have a Diplomat dish washer, sorry don't know its model number. You set it to run as normal and close the door. It gives two beeps to indicate it has started, starts to fill with water and a few minutes later stops. When you open the door, the message E5 is on the panel in the door, the detergent box has not opened. Can anyone help please?