how can i fix my kenwood dish washer?

Hi i have a kenwood dishwasher kdw12st3a can you help, i have water coming out in to the bottom of the machine from the (overflow pipes) that enter in to the sump at the front near the base of the door, the washer works fine untill the water builds up in the bottom and trigers a switch that stops the washer from working and comes up falt code E4,when i tilt the washer to drain the water from the bottom of the washer it will work again, i dont know why this keeps happening can any one help please thanks mike