January 5

Microwave Turns on When Door Is Closed | Our Full Troubleshooting Guide


Author: Colin Ma
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If your microwave turns on when the door is closed, then there is a chance that something is wrong with it. You may need to clean the door's sensor. By opening and closing the microwave's door multiple times while it is not in use, the device will learn when you want to start cooking and when you do not.

There are several parts of a microwave that can go bad. Most microwaves have two small plastic bars that detect when the door is open or closed.

This way, the microwave knows whether or not to start cooking. If something is obstructing or covering these bars, it may think that the door is shut and start cooking as soon as you press the start button.

Microwave Turns on When Door Is Closed: Some Things to Check Out

The Clock Is Set to "On"

Did you know your microwave's clock defaults to "on"? That means if your microwave doesn't detect any activity for about ten minutes (or however long it takes to heat something), it will assume you are done and start cooking.

To turn the clock "off," open the microwave door and press "stop/clear." Afterward,  push any button on the keypad except for "start" or "defrost." It should be enough to clear your settings and stop your microwave from turning on when you close the door.

display on the microwave oven showing 9:35 am

The Door Switch is Broken

If your oven turns on when the microwave door closes but does not turn back on when the door opens, your problem maybe with one of its door switches.

Every microwave has at least two door switches. If one malfunction, then it will experience the same problem. Check them with a voltmeter to see which one is broken. The door switches actuate the microwave's 'start' switch; thus, if one is faulty, then the start button won't work.

The Sensor Has Dirt or Food

If your microwave turns on when you close the door, but you have already pressed "stop/clear," then there may be something on its sensor. Microwaves have sensors to detect when the food inside has been heated to a specific temperature.

If there is some dirt or residue on the heat sensor panel, it will assume the food is still cooking and start up again. Clean it off with some warm water and soap until you can no longer feel any residue.

a person cleaning the microwave door

The Magnetron Maybe Broken

The magnetron is the central part of the microwave where the electricity flows through to create microwaves. It may be that the magnetron in your oven is broken and needs a replacement. It is not costly, but you will need professional advice and help unless you feel comfortable separating and replacing the piece.

Shut the Door Slowly

If none of these work for you, try shutting the door slowly to see if your microwave can detect its closing. If this works, then maybe there is something blocking one of its sensors. Move any items out of the way to get a better look at them.

The Membrane Keypad Could Be Faulty

If none of your sensors are broken, then maybe the membrane keypad is acting up. Unplug the microwave and leave it for an hour or so to check this. It will reset it and clear out any issues with its memory. Plug it back in and see what happens when you try to close the door.

a female person pressing the keys on the microwave oven keypad

The Control Board Can Be Faulty

If your door sensor is exemplary, but the microwave still turns on when you close it, then there may be a problem with its smartboard.

The board controls the sensors and all of the features of microwaves, such as "add 30 seconds" and "popcorn ." These boards can be expensive to replace, but it is easy for somebody who knows what they are doing.

Try Replacing Door Parts

If nothing else helps, try replacing some of its parts. Unplug the microwave and use a screwdriver to take off all the screws. It should be easy enough to know what you are doing and can easily follow directions.

Once it is open, look at the door interlock switch and see if you notice anything out of place. If the door switches fail, try replacing them first before investing in a new microwave if you see anything.

a white microwave with opened door

Do Not Use the Microwave Again Until You Fix It

If you followed all the steps above and nothing happens, stop using your microwave until you have resolved the issue. The problem might be with its build, and that means if something goes wrong again, you are most likely out of luck.

Many microwaves are made with multiple safety features to prevent them from turning on by accident. However, if one is broken, then there is a good chance that your microwave will start up again at some point.

The best thing you can do is keep looking for parts until you find the problem and how to fix it. Once you do, you can go back to using your microwave.

two people standing by the microwave oven

What Does It Mean if Your Microwave Turns on by Itself?

A microwave can cook your food whenever you shut the door if its sensors are obstructed. If yours turns on by itself, then it might be time to replace your microwave or call someone in to fix the problem.

Moreover, a microwave that starts cooking on its own may have a magnetron problem. You can fix this yourself or call a professional to come and do it for you.

If your microwave does not stay off after ten minutes of inactivity, something is blocking its sensors. Clean them until you can no longer feel any residue.

Why Does My Microwave Keep Running After the Timer Goes Off?

If your microwave keeps running after the timer has gone off, then it may be time to replace the timer. The timing of microwaves is controlled by a tiny part that tends to go wrong.

Therefore, if yours does not shut off despite repeated attempts at pressing the timer button, you will probably need to get a new one. Unfortunately, this requires some electrical knowledge, so it would be best to call in a professional if you want to replace your timer.

If the door switches are broken, your microwave will start back up when you shut the door again, no matter how long you wait. If this happens, it may be time to call a professional to replace them.

closeup of a microwave timer

How Do I Know if My Microwave Door Switch Is Bad?

If your microwave continues to cook when you shut the door but shuts off after opening it again, then its door switch is bad. A common way microwaves detect that the door is now open instead of shut is by measuring the voltage difference between two wires.

If these wires lose their voltage when the door is shut, it turns on as soon as you open it. Check them with a voltmeter to see which one is bad.

How Do I Fix My Microwave Door Switch?

If you want to fix your microwave yourself, you will need some electrical knowledge. You can replace the switch by opening up your microwave and following some wiring diagrams.

Make sure that you know what you're doing before attempting any repairs, as microwaves have high voltage. If released from a faulty wire or connection, this could result in an electrical shock that can be extremely dangerous.

However, if you've had success fixing some other parts on your microwave, then replacing the door switch may be something you can do yourself.

You can start by opening your microwave and looking at the wiring diagram to see which wires control the door switch. If you know what you are doing, replacing them will not be too difficult.

a person fixing the microwave door

Why Does My Microwave Turn On When I Shut the Door?

Dirty microwave sensors can turn your microwave on when you shut the door. If this happens, then cleaning them may fix the problem. Your microwave might also be reacting to a magnetron that isn't working correctly, which can occur if there is too much dust or residue in your microwave. The best way to clean it out is with some soft clothes and denatured alcohol.

If your microwave is turning on every time you shut the door because of broken switches, replacing them may eliminate the problem. While it is not too tasking to replace the switches yourself, calling in a professional might be your best bet if that doesn't work.

Why Do the Lights Come On in My Microwave?

The light bulb in your microwave may come on if the door sensor is broken and it is trying to heat up. If you see this, unplug your microwave and wait a while before using it again.

Alternatively, you can replace its switches or door detection system. Otherwise, if the light won't turn off, then the power fuse is probably blown, and you'll need to replace it (see also 'How to Replace Microwave Light?').

closeup of a microwave oven
To help you with that we share our thougts on a range of microwave ovens for different purposes: 

Microwaves for Home Use

At home you'll need a microwave oven that would complement your culinary skills. Home based microwave should be large enough and powerful enough to cook for medium to large sized family. Fortunately, we reviewed microwaves for home use from both budget as well as premium budget range.

Simple and Basic Microwave Ovens

Having minimal features and small size, naturally makes a basic microwave an affordable one too. A simple microwave oven is a small-midsize model that is suitable for simple tasks, accommodates smaller sized dinners plates or serves up to a small family (see here why an empty plate does not heat up in the microwave, too).

Large Countertop Microwave Ovens

The size of a microwave oven is determined by its interior capacity measured in CU FT or liters and large microwave ovens by definition go beyond 1.6 CU FT. Make certain that you take the external dimensions into account especially if you have filled kitchen or if you plan on designating a dedicated spot for your large microwave oven. 

1200 Watt Microwave

If you are looking for the most powerful microwave ovens for home use, then you will certainly find them with a 1200 watt power rating. High powered microwave ovens are heavy duty and thus feature expensive components and are very large. Also, premium ovens in this power category offer cutting edge technology, but at a higher cost.

Retro Microwave Ovens

These ovens are generally not large nor do they feature a high power. Hence, they mostly appeal to style. A retro microwaves will usually appeal to your need for aesthetics as well as have all the regular functions of a microwave oven. Fortunately, most retro ovens are affordable.


If you want to avoid this problem as much as possible, try using your microwave oven less. Only heat small quantities of food and use the lowest power setting available.

If you must keep it plugged in all the time, make sure to unplug the microwave overnight and occasionally for an hour or so. It will serve as a break and give your oven time to cool off.

Microwaves are heat-sensitive devices. If the microwave does not have enough time to cool off, it will start back up when you re-open the door. You can also try covering the microwaves sensor with an aluminum foil while it is not in use to help prevent any false readings.

About the author

Colin Ma

An avid home chef, Colin is equally passionate about delicious meals as well as the latest cooking appliances. He's also a keen writer about cooking-related topics.


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