If the water flow to the dishwasher doesn’t automatically shut off, the float switch is faulty, the timer is stuck on “Fill,” or the water inlet valve is stuck open. To test the float switch, you’ll need an inexpensive volt-ohm meter (or multi-tester).

1) Unplug the dishwasher.

2) Reach into the cabinet, and lift up the dome-shaped plastic float switch. If it doesn’t lift up, remove the plastic top from the stem, scrub the stem clean, and then replace the dome. If it moves up and down freely, go on to Step 3.

3) Note which wires are attached to the float switch’s terminals, and, using small pieces of tape, label them for future reference should you need to replace the switch.

4) Set the volt-ohm meter’s dial to Rx100 and touch the two probes to the terminals. When you lift up the float, the tester’s needle should show an infinity reading, and, when you let the float drop, the needle should show a 0 reading. If it doesn’t, the switch is broken and needs replacing. Unscrew it from the tub, take it to your local hardware store or home improvement center, buy an identical replacement part, and then install it and hook it up.