How to Replace the Float Microswitch in Your Dishwasher

A flooded kitchen floor and a dishwasher that won’t fill sound like opposite problems, but they share a suspect: the float microswitch under the tub, whose whole job is to say ‘that’s enough water.’ Stuck one way, it never lets water in; stuck the other, it never says stop.

We’ve replaced more of these than we can count, and it’s one of those jobs that sounds intimidating but really isn’t. Plan for about 30 to 45 minutes, and you’ll have it handled.

Full safety notes below

What the Float Microswitch Does

Every dishwasher has a float assembly inside the tub: that small dome or cylinder, usually near the front corner of the tub floor. As water fills the dishwasher, that float rises. When it reaches a certain height, it physically pushes down on the float microswitch mounted beneath the tub floor. That switch then tells the fill valve to shut off.

It’s a dead-simple mechanical system, and that’s exactly why it’s so reliable, until it isn’t. The microswitch itself is a tiny electrical switch with a lever or actuator arm. Over time, the internal contacts wear out, corrode, or get stuck. When that happens, the switch can’t accurately signal the water level anymore.

The float and the float switch work as a team. If you’ve already confirmed your float moves freely up and down (no debris, no sticky residue holding it in place), and you’re still having fill issues, the microswitch is almost certainly your problem. If you’re working on a GE model specifically, our guide on how to replace the float on a GE dishwasher walks through the float assembly side of things in more detail.

Signs Your Float Microswitch Has Failed

Here’s what a bad float microswitch typically looks like in practice:

• The dishwasher won’t fill with water at all: you start a cycle and hear humming or clicking, but no water enters the tub

• The dishwasher overfills and water leaks onto the floor

• The fill valve runs continuously, even when the tub is full

• An error code related to water level or overflow appears on the control panel

• The dishwasher starts a cycle but immediately drains without washing

An overfill situation is the one you want to catch fast. If water is spilling out of your dishwasher, kill the power immediately and mop up before doing anything else.

Tools You’ll Need

This is a basic repair. Here’s what to have on hand:

• Phillips-head screwdriver

• Quarter-inch nut driver (or a small socket set)

• Multimeter

• Towel or small container for catching residual water

• Flashlight or headlamp

A headlamp is especially useful here because you’ll be working underneath the dishwasher or at awkward angles where holding a flashlight isn’t practical.

Safety First

Disconnect the power before touching anything. Either unplug the dishwasher from the outlet under the sink or flip the breaker. Don’t just turn the dishwasher off. Actually cut the power. You’re going to be handling wiring, and the microswitch sits near the water inlet valve. Electricity and residual water don’t mix.

Also, turn off the water supply to the dishwasher. The shut-off valve is almost always under the kitchen sink. This keeps water from flooding in while you’re working on the fill system.

Step-by-Step: Replacing the Float Microswitch

1. Remove the lower access panel. This is the kick plate at the bottom front of the dishwasher. It’s usually held on by one or two screws, sometimes Phillips, sometimes quarter-inch hex heads. Pull it off and set it aside.

2. Locate the float microswitch. Look up under the tub near the front, typically on the left side, though some brands mount it on the right. The float stem drops through a hole in the tub floor, and the microswitch is mounted right below that hole. You’ll see a small switch body with a lever or plunger that the float stem presses against, plus two or three wires connected to it.

3. Test the old switch with your multimeter. Before pulling anything apart, confirm the switch is actually bad. Disconnect the wire connectors from the switch terminals. Set your multimeter to continuity or resistance (ohms). With the float in the down position (not pressed), you should see continuity through the normally closed terminals: that’s the circuit that allows the fill valve to run. Press the switch lever to simulate the float being raised. Continuity should break on those terminals. If the switch shows no continuity in either position, or shows continuity in both, it’s failed. Replace it.

4. Photograph the wiring. Take a quick picture with your phone before disconnecting anything. Float microswitches usually have two or three terminals, and getting the wires back on the correct terminals matters. Here’s what catches most people off guard: the terminals often aren’t labeled clearly, and swapping common and normally closed will give you the exact opposite behavior you want.

5. Remove the old switch. The microswitch is typically held in place with a small mounting screw or a plastic bracket that clips into the tub floor. Remove the screw or press the retaining tab, then slide or pull the switch free. Some models use a simple friction fit where the switch pushes into a mounting slot. Gentle wiggling gets it out.

6. Install the new microswitch. Slide the replacement switch into the same mounting position. Make sure the actuator lever or plunger lines up directly under the float stem: if it’s off by even a small amount, the float won’t engage the switch properly. Secure the mounting screw or snap the bracket back into place.

7. Reconnect the wires. Using your photo as reference, push the wire connectors onto the correct terminals. They should click on firmly. Give each one a gentle tug to make sure it’s seated. A loose connection here will mimic a failed switch and send you in circles.

8. Reassemble. Reinstall the lower access panel. Turn the water supply back on. Restore power.

Testing the Repair

Run a short wash cycle and watch what happens. Open the door a couple of minutes into the cycle: there should be water in the tub, but not an alarming amount. The water level should sit just below the door opening, roughly at the bottom of the door gasket.

If the tub fills and stops appropriately, you’re done. If it overfills or doesn’t fill, double-check your wiring connections. Nine times out of ten, when a new switch doesn’t fix the problem, the wires got swapped on the terminals.

While you’re at it, lift the float dome inside the tub by hand and listen. You should hear a faint click from underneath as the float engages the new microswitch. That click tells you the mechanical connection between the float and switch is solid.

When you’re ready to find the right replacement switch, grab your model number and find the exact part for your model. The model number is usually on a sticker or plate along the inside edge of the door: open the door and check the left side or top edge.

Need More Help?

If you’ve swapped the microswitch and things still aren’t right, it could be a stuck float, a faulty water inlet valve, or a control board issue. Before going down that road, post your model number and symptoms on our repair forum. Our techs and community members troubleshoot these kinds of problems every day and can help you zero in on the real culprit.

Written by: AppliancePartsPros Team