How to troubleshoot and fix common dishwasher problems, including a dishwasher that doesn’t run, fill or drain. Also, how a dishwasher works.
If your dishwasher stops working properly, it isn’t the end of the world. But it does put the kibosh on one of the luxuries that adds to your quality of life. Because fixing a dishwasher isn’t usually an emergency, you have the opportunity to troubleshoot problems and try solving them yourself before calling an appliance repair person.
The following should help you handle repairing a dishwasher that doesn’t run right—or doesn’t run at all. If your dishwasher leaves spots or film, or just does a poor job of cleaning, see Dishwasher Washes Poorly.
HomeTips Pro Tip: Before you begin troubleshooting, unplug the dishwasher or shut off its electrical circuit. Also turn off the its water supply valve. Don’t work inside the dishwasher immediately following a cycle because the dish-drying element at the bottom may still be hot.
Dishwasher Doesn’t Run
If you turn on the dishwasher and absolutely nothing happens, a lack of electrical power is likely the cause:
1Be sure the power is on, the door is latched, and the control is engaged. If absolutely nothing happens—in other words, nothing on the control panel lights up and there are no other signs of life—the appliance may not be receiving power.
Look where the dishwasher’s cord plugs into a receptacle. Check to see if that outlet is a GFCI receptacle with a reset button. If it has a reset button, push the reset. In the condition where the receptacle doesn’t have a reset, or where the dishwasher’s cord is hard-wired directly into the electrical box, look for any other receptacles in the kitchen that have a reset and and try resetting them. (This is a long shot, but it’s easy to do and may solve the problem if the dishwasher is on the same circuit.) To test a receptacle for power, you can also just plug a working hand-held appliance into it.
2Check the electrical panel that serves the dishwasher for a tripped circuit breaker or blown fuse. If you find one, switch the breaker to OFF and then back to ON or replace the fuse.
3Check dishwasher switches & timer. If electrical power is available to the dishwasher but the appliance doesn’t run, the problem is likely a defective door switch, timer, or selector switch. To solve a door switch problem, you may be able to adjust the door latch’s strike slightly, using a screwdriver (turn off the power to the dishwasher at the electrical panel first). If the problem is with the timer or selector switch, it’s best to call an appliance service person.
Dishwasher Doesn’t Fill
If your dishwasher runs but doesn’t fill, either something is wrong with the water supply system or it is draining water too soon.
1Make sure the water is turned on. Check the hot water supply stop valve, normally located under the sink. Open it all the way by turning it counterclockwise. If you can’t think of any reason this would have been turned off since the last time the dishwasher worked, go on to the next step.
2Turn off the power to the dishwasher. When the dishwasher is cool (in other words, not right after a wash cycle), look for the float inside the dishwasher; this is usually a small plastic dome or cylinder mounted inside at the tub’s base, near the front. When you move most types of floats up and down, you can hear them click because their spring-loaded action trips a lever. Lift out the float mechanism, and clean around the float tube. Many floats require disconnection from below; to do this you’ll have to remove the lower access panel. Rinse off the float, replace it in the tube, and make sure it moves up and down freely.
3Shut off the hot water valve to the appliance. Locate the water intake valve, behind the dishwasher’s bottom front panel. Disassemble the valve to reveal the screen. Clean any debris from the screen and reassemble the valve. If the screen appears clear, call an appliance repair person. Any of several parts—including the water inlet valve, pressure switch, and timer or selector switch—may be faulty.
Dishwasher Doesn’t Stop Filling
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 multimeter like the one shown here, which costs under $25 online. Less expensive multimeters are available, too.
1Unplug the dishwasher. 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 2.
2Note 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.
3Set 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, replace the switch. 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.
Dishwasher Doesn’t Drain
Following a cycle, a small pool of clean water inside the tub is normal. An excessive amount of water indicates an improperly-working pump, a clogged drain hose, or the clogged house drain lines.
If dirty water spews from the air gap, check the drain line for a kink or clog. (If you’ve recently installed a garbage disposer, be sure the knockout plug for the dishwasher was removed when the connection was made; see your disposer instructions.)
1Remove the cover from the air gap at the top of the sink (usually a short chrome domed cylinder that sits at the back of the sink), and, using a stiff wire, clean it out. Also check the entire length of the drain hose for kinks or blockages, especially at the drain connection to the disposer or drain line.
2Once the dishwasher is cool, shut off the power to it, and—if your dishwasher is made to allow this—remove the strainer (shown at right), located under the bottom spray arm at the base of the cabinet. Unscrew the hubcap, lift the spray arm off, and remove any clips that hold the strainer to get it out. Scrub it clean with a brush and then replace it.
3Determine whether the sink trap or house drain line is clogged. If the sink backs up, you’ll need to check for a drain clog. If this is the problem, see Sink & Drain Repairs.
4If the dishwasher still doesn’t drain properly, the drain hose may be clogged or the drain valve may need replacement. You can check the drain hose for obstructions, but this usually involves pulling the dishwasher out from under your counter to access the hose, disconnecting the hose at both ends, and flushing it out with a faucet or garden hose, or replacing it with a new hose (see dishwasher hose repair kits).
Repair Dishwasher Leaks
If you have nuisance water leaks around the base of your dishwasher, you may be using a detergent that is sudsing too much. Cut back on the amount of detergent you use and see if that makes a difference.
Improperly loaded dishes can cause water to spill through the door vent. Leaks from the door itself usually come from a faulty door gasket or faulty door tightness adjustment.
Also make sure the dishwasher is sitting level (you can adjust the front feet up or down, and many units have some type of levelers at the rear).
Water under the dishwasher may be originating from a leaky hose or loose hose connection. Remove the lower front panel and check the hoses. The pump seal may be defective, too; replacing this is a job for a repair person.
An older dishwasher may have become corroded at the bottom, but this is fairly uncommon. However, if this is the case with your dishwasher, it’s definitely time to invest in a new one.
How a Dishwasher Works
Despite the magic it performs in the kitchen, a dishwasher is actually quite simple—it is essentially a watertight box that sprays dishes with hot water and soap, drains out the dirty water, and then dries the dishes.
All of this is operated by controls that may be very simple or quite complex. The controls tell the system when to spray, when to release detergent from a dispenser, when to extract water from the tub and pump it back through the system, when to rinse and remove the rinse water, and when to turn on the heating element.
Hot water travels to the interior of a dishwasher through a supply hose that connects to a water supply valve, typically mounted under the sink. To shut off the water to the dishwasher, you close this valve. The other end of the supply hose connects to a water inlet valve inside the dishwasher. The inlet valve, electronically connected to the controls, opens and closes to supply water to spinning spray arms. These spray arms, usually at both the top and bottom of the tub, are like a high-pressure sprinkler system that sprays the dishes clean.
Dirty water collects at the base of the interior chamber, moves through a filter, and gets pumped back through the system during the early wash cycles. When all of the cleaning and rinsing cycles finish, the pump sends the dirty water out through a drainpipe. Then an electric heating element heats up to dry the dishes.
Problems with proper cleaning usually arise if the water is not hot enough (140 degrees F. is optimal) or if your water is too hard. How hard is your water? See How to Test for Hard Water. Also, when operating your dishwasher, use the right amount of soap for your water type—1 teaspoon per grain of water hardness.
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