The E1 error code may occur due to a blocked non-return valve of the drain pump. To access the drain pump, remove the bottom panel and the side panel and unscrew the pump from its casing. Try rotating the pump counter-clockwise to get it out. Remove the drain hose and pull the non-return valve out of the pump. Check the drain hose for debris and clogs: most likely, you will find a lot of stuff there. Flush the hose and reassemble the machine.
Other Kenwood dishwasher error code: