How to Fix a Dishwasher That Won't Fill With Water (2026)

Frequently Asked Questions

Where is the water supply shutoff for a dishwasher and how do I check it?

The dishwasher supply shutoff is almost always under the kitchen sink. Look for a small valve on the hot water supply line — usually a brass angle stop or straight stop valve with a handle or a flat-head slot. Turn it fully counterclockwise to open. Many are never touched and can seize in a partially closed position over years. If the handle turns but the valve does not open fully, replace the angle stop. Also confirm the supply line connecting the valve to the dishwasher is not kinked — a kinked braided steel line restricts flow enough to prevent filling.

How do I fix a dishwasher float switch that is stuck?

The float switch is a small plastic dome or cylinder located in the front corner of the dishwasher tub floor. It floats up when the water reaches the correct level and cuts off the fill valve. When it sticks in the up position, the dishwasher thinks it is full and never opens the inlet valve. To fix: (1) Open the dishwasher and locate the float — it looks like a small plastic mushroom cap. (2) Lift it up and let it drop — it should move freely up and down with no resistance. (3) If it feels sticky or does not drop freely: remove it (usually just lifts straight off or twists off) and clean the guide tube underneath with warm soapy water. Food debris and hard water scale are the usual culprits. (4) Reinstall the float. If it still sticks after cleaning, replace the float assembly ($10–$20). (5) You can also test the float switch electrically: with the dishwasher unplugged, remove the access panel below the door, locate the float switch (connected by two wires at the bottom of the float tube), and use a multimeter set to continuity. With the float in the down position, the switch should show continuity (closed circuit). With the float up, no continuity. A switch that shows no continuity in either position is failed and needs replacement.

How do I test and replace the water inlet valve?

The water inlet valve is a solenoid valve mounted behind the lower access panel of the dishwasher. It has a water supply line connecting to it and electrical terminals for the solenoid coil. To test: (1) Unplug the dishwasher. (2) Remove the lower kick panel (usually 2–4 screws). (3) Locate the inlet valve — a plastic body with a screen inlet, water outlet hose going into the tub, and two electrical terminals. (4) Use a multimeter on the solenoid terminals — a good solenoid coil reads 200–500 ohms. An open reading (OL or infinity) means the solenoid coil is burned out and the valve needs replacement. (5) Also check the inlet screen: unscrew the supply line from the valve inlet and look inside for a small mesh screen. Calcium and sediment clog this screen and reduce or stop water flow. Clean it with a toothbrush or replace the valve. (6) To replace: turn off the supply shutoff, disconnect the supply line, unclip or unscrew the valve from its bracket, transfer the outlet hose, plug in the new valve, and reconnect the supply line. Replacement valves are $20–$50 and model-specific — order by your dishwasher's model number.

What does the door latch interlock do and how do I fix it?

The door latch interlock is a safety switch that prevents the dishwasher from running if the door is not fully latched. When the latch engages, it presses a microswitch that signals the control board to allow the fill cycle. If this switch fails or the latch does not engage fully, the dishwasher will appear to start (display may light up, control panel responds) but will not fill. To diagnose: (1) Close the door firmly and listen for an audible click from the latch mechanism. (2) Inspect the latch hook on the door and the strike on the tub frame — if either is bent, broken, or misaligned, the latch will not engage the switch. (3) With the dishwasher unplugged, access the latch assembly (typically 2–4 screws inside the door panel). Test the door switch with a multimeter for continuity when the latch is engaged. (4) Replacement door latch assemblies typically run $15–$40. They include the latch hook, strike, and switch as one assembly. This is a straightforward repair requiring a screwdriver.

My dishwasher hums when I start it but doesn't fill. What does that mean?

A dishwasher that hums but does not fill is almost always the water inlet valve receiving power but failing to open. The hum is the solenoid coil energizing but the valve plunger or diaphragm is stuck. This happens when: (1) Mineral scale has built up on the valve's internal diaphragm or plunger, preventing it from opening when energized. The valve needs replacement — cleaning rarely restores a mechanically stuck valve. (2) The supply pressure is too low — inlet valves require at least 20 PSI to open. If your home water pressure is low (check with a pressure gauge at the supply valve) or the supply shutoff is partially closed, the valve may hum but not open fully. (3) Less commonly, a failed control board relay may be sending incorrect voltage to the valve. If a new valve does not fix the hum/no-fill problem, have the control board checked.

How do I test if the dishwasher control board is causing the no-fill issue?

Control board diagnosis is a last resort after checking all mechanical and electrical components. The control board sends voltage to the inlet valve at the start of the fill cycle. To verify the board is sending voltage: (1) With the dishwasher plugged in and a fill cycle started, use a multimeter (set to AC voltage) to measure voltage at the inlet valve terminals. You should read line voltage (120V in the US) when the fill cycle is active. (2) If no voltage is reaching the valve during the fill cycle and the door switch and float switch both test good, the control board output relay for the inlet valve has likely failed. (3) Control board replacement is $80–$200+ and model-specific. Compare the cost to the dishwasher's age and replacement cost — a board repair on a 12-year-old dishwasher is rarely worthwhile. (4) Before replacing the board, also check the wiring harness between the board and the inlet valve for loose connectors or broken wires — these are more common than board failures.

Dishwasher not filling: (1) Check the water supply shutoff valve under the sink — it may be closed or partially closed. (2) Check the float switch inside the tub — it can stick in the raised position and tell the dishwasher it is already full.

A dishwasher that won’t fill is frustrating — but most causes are straightforward to diagnose and fix yourself in under two hours.

What You Need

Before you start, gather these tools and parts. Having everything on hand prevents mid-repair trips to the hardware store.

• Multimeter for appliance testing — essential for testing the inlet valve solenoid and door switch
• Dishwasher water inlet valve — the most common parts repair; order by your model number
• Float switch assembly replacement — inexpensive fix for a stuck float
• Door latch assembly — if the latch is broken or won’t engage the interlock switch
• Braided steel dishwasher supply line — replace if kinked or older than 10 years as preventive maintenance
• Appliance screwdriver set — TORX and Phillips heads are needed for most dishwasher panels

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Step 1: Check the Water Supply Shutoff

This is the fastest check and costs nothing. Open the cabinet under the kitchen sink and locate the dishwasher supply line. Follow it to a shutoff valve — typically a small angle stop with a lever or slotted handle.

Turn it fully counterclockwise (open). If it already appears open, close it fully and re-open it to confirm it is not partially seized in an intermediate position.

Also inspect the supply line itself for kinks. A braided steel line that has been pinched against the cabinet wall can restrict flow enough to prevent the dishwasher from filling. If the line is kinked or older than 10 years, replace it now — a supply line failure under the sink causes significant water damage.

After confirming the supply is open, run a short cycle and listen for water entering the tub.

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Step 2: Check and Free the Float Switch

Open the dishwasher door and look at the tub floor near the front corners. You will see a small plastic dome, cylinder, or mushroom cap — this is the float.

Press down on the float and release it. It should move freely up and down. If it feels gritty, sticky, or does not spring back:

1. Lift the float straight up to remove it (no tools needed on most models).
2. Clean the guide tube with warm soapy water and a bottle brush. Remove any food particles or lime scale.
3. Clean the underside of the float cap.
4. Reinstall and confirm it moves freely.

Start a cycle and listen for filling. If the float moves freely but the dishwasher still does not fill, move to Step 3.

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Step 3: Inspect the Door Latch and Interlock Switch

Close the dishwasher door firmly and listen for the latch to click into place. A door that appears closed but has not engaged the latch interlock switch will not allow the fill cycle to begin.

Open the door and inspect the plastic latch hook on the door and the strike/receiver on the tub frame. Look for:

• Cracked or broken plastic on the latch hook
• Misalignment between the latch and the strike
• A bent door or warped tub opening that prevents full closure

If you can see and feel the latch engaging the strike, the issue may be the microswitch inside the latch assembly. Unplug the dishwasher, remove the inner door panel (typically 6–8 screws around the perimeter), and access the latch assembly. Test the switch with a multimeter for continuity when manually pressing the latch mechanism.

Replace the door latch assembly if the switch has failed or the plastic components are broken.

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Step 4: Test and Replace the Water Inlet Valve

The water inlet valve is the most common cause of a dishwasher that won’t fill. It is a solenoid-operated valve that opens when the control board signals the fill cycle.

Testing the valve:

1. Unplug the dishwasher.
2. Remove the lower kick panel (typically 2–4 screws at the bottom front).
3. Locate the inlet valve — it has the supply line connecting to its inlet and a plastic hose going to the tub, plus two electrical terminal blades.
4. Disconnect the electrical terminals and test across them with a multimeter set to resistance (ohms). A good solenoid reads 200–500 ohms. An open reading (OL) means the solenoid is burned out.
5. Also inspect the small mesh screen at the valve’s water inlet: disconnect the supply line and look inside with a flashlight. A clogged screen appears brown or white with mineral deposits.

Replacing the valve:

1. Turn off the supply shutoff under the sink.
2. Have a towel ready — residual water will drain from the line.
3. Disconnect the supply line from the valve inlet.
4. Disconnect the outlet hose from the valve (spring clamp or screw clamp).
5. Unscrew or unclip the valve from its mounting bracket.
6. Transfer the bracket to the new valve.
7. Reconnect the outlet hose, supply line, and electrical terminals.
8. Turn the water back on, reinstall the kick panel, and run a test cycle.

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Step 5: Check Water Pressure

Dishwasher inlet valves require a minimum of 20 PSI of household water pressure to open fully. If your home has low water pressure or if the supply shutoff is only partially open, the valve may receive power but not open.

Connect a water pressure gauge to a nearby hose bib or laundry connection and check your pressure. Normal residential pressure is 40–80 PSI. Below 20 PSI at the dishwasher supply causes fill failures.

If pressure is adequate but the dishwasher still does not fill after replacing the inlet valve, the control board may not be sending voltage to the valve during the fill cycle.

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Step 6: Verify Control Board Output (Advanced)

If all mechanical and electrical components test good, the issue may be the control board relay that powers the inlet valve.

With the dishwasher plugged in and a fill cycle initiated, carefully measure AC voltage at the inlet valve terminals using a multimeter. You should read approximately 120V when the fill cycle is active. If no voltage is present despite the door switch and float switch testing good, the control board has failed.

Control board replacement is $80–$200 depending on the dishwasher model and age. On older dishwashers, compare repair cost to replacement cost — a dishwasher over 10 years old with a failed control board is often better replaced than repaired.

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When to Call a Professional

Most dishwasher fill failures are DIY-fixable using the steps above. Call a technician if:

• You confirm all components test good but the dishwasher still does not fill
• The control board needs replacement and the quotes feel expensive relative to replacement cost
• You find water damage around the supply line connection that suggests a previous slow leak

A qualified appliance technician can diagnose the issue in one visit, typically charging $80–$150 for the service call plus parts.

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Related Reading

• How to Fix a Garbage Disposal — the garbage disposal knockout plug can block dishwasher drain flow on new installs
• How to Fix Low Water Pressure — whole-home low pressure affects dishwashers, showers, and faucets
• Annual Home Maintenance Schedule — includes appliance maintenance tasks to prevent future failures
• How to Fix a Leaking Refrigerator Water Line — water supply line repair for ice makers and refrigerators