The part(s) or condition(s) listed below for the symptom Dishwasher overflowing are ordered from most likely to least likely to occur. Check or test each item, starting with the items at the top of the page.
The water inlet valve is an electrically-controlled valve that opens to allow water to enter the dishwasher. Depending on the model, the valve stays open either for a set length of time or until the dishwasher has enough water. However, if the water inlet valve doesn’t shut off after the dishwasher has enough water, the dishwasher will overflow. If water drips into the dishwasher when the door is open, or if water collects at the bottom of the dishwasher while it is not use, you may need to replace the water inlet valve.
The float switch actuates in order to prevent the dishwasher from overflowing. If the float switch is defective or stuck, it might not stop the dishwasher from overflowing. If the float switch is defective, replace it.