The E3 error occurs due to moisture. Most likely, there is a leak or high condensation. First, you need to dry your washer. Unplug it for about 3 days. Check the door seals. Not unlikely, they are not tight enough and are letting water through, and it may get out of the wash section and affect the electronics. This must be fixed immediately: most likely, you have to replace the seals.
Other Kenwood dishwasher error code: