The part(s) or condition(s) listed below for the symptom Dishwasher won't fill 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 opens to allow water to enter the dishwasher. If the water valve is clogged or defective, water will not flow into the dishwasher. Water inlet valves are not repairable—if the valve is defective, you must replace it.
Some dishwashers have a safety float in the front corner of the tub to prevent the dishwasher from overfilling with water. If an object is stuck under the float, the dishwasher may not fill with water. If you find anything stuck under the float, remove it and the dishwasher should start filling properly.
A dishwasher's main control board provides power to nearly every electrical component in the dishwasher. A faulty board may be unable to supply power to the water inlet valve, preventing it from opening and allowing the necessary water to fill the tank.
You should confirm that the dishwasher's water supply shut-off valve is in the "On" or open position. The water supply shut-off valve is usually located under the sink and is connected to the hot water line.
The float switch is a safety designed to shut off the water inlet valve if the dishwasher is overfilling. If the float switch is defective or stuck, it might stop the dishwasher from filling correctly. You can use a multi meter to test the float switch for continuity. If the float switch is defective, replace it.
A dishwasher's control board provides power to nearly every electrical component in the dishwasher. A faulty board may be unable to supply power to the water inlet valve, preventing it from opening and allowing the necessary water to fill the tank.
Over time, calcium deposits can build up in the water supply valve or in the small filter screen inside the water inlet valve. If the water inlet valve is clogged with sediments, the dishwasher won't fill properly. Before working on the water line, first shut off the water supply. Inspect the valve to determine if it is clogged. Also, the inlet valve requires good water pressure to function properly. You can check the water flow at the kitchen faucet to help determine if the home's water pressure is sufficient or not.
A dishwasher pressure switch is the component that will send a signal to shut off the water inlet valve once an appropriate amount of water has entered the tank for a wash cycle. If the pressure switch is malfunctioning, it may prevent the inlet valve from opening and filling the tank. You can use a multimeter to test the pressure switch's terminals for appropriate changes in electrical continuity before and after blowing air into the attached pressure tube. If the switch does not test appropriately, it should be replaced.