5 Reasons Why a Microwave Might Turn On by Itself

The front to a microwave oven.
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These days a microwave oven in the kitchen is a staple of nearly every home. Rarely do you find someone without one. Depending on the size and quality of the unit—a microwave can function for several years before you need to replace it.

A common problem in many models is that the microwave turns on by itself. Some models, even after they are unplugged, will even store enough power to turn on by themselves.

Anytime a microwave begins to operate without being turned on, it becomes a fire hazard.

When this happens, the oven needs immediate repair or replacement. If neither is possible—then the microwave needs to be unplugged and its door kept open when not in use. If the faulty oven is used, close supervision is recommended in case of fire. Here are five reasons why a microwave might turn on by itself.

Faulty Board and Switches

In the past, customers reported their microwaves from a particular manufacturer turning on by themselves. Even when the customers hit “cancel” on the microwave—it would come back on. This issue was not a small one.

It was discovered after research that a faulty board or switch on the microwave could lead to such an issue. In such a case as this, contact the manufacturing company and ask them to replace the board or switch.

Stuck Switches

If the microwave light and motor turns on, but there is no heat, and the turntable does not spin—it could be that the interlock switch in the door is stuck. It might also be that the interlock relay on the control panel is stuck.

Heat Sensor Panel

Many times microwave buttons are heat sensitive. You do not really have to press any buttons, but the warmth of your finger will be enough to press the buttons.

If this is how your microwave works and it is an over-the-stove model, it may be that the heat from your oven or steam from a pan on the stove is tricking the sensor panel into thinking that someone is touching the buttons.

Control Panel

If the microwave turns itself on and unplugging and resetting it does not resolve the issue, then the problem might be in the control panel.

The touchpad could be defective, or something has gone wrong in the control board. If the control panel is supplying voltage to the cooking components when it has not been told to do so by the user, then something is likely wrong with the control panel.

Membrane Keypad

The membrane keypad, although not available as a separate part, can be replaced. This is a relatively easy do-it-yourself kind of a job. Since it’s not sold separately, you will have to order the control panel frame assembly, which will come complete with a new membrane keypad installed.

You will need to remove the existing control panel frame assembly from your microwave. With that done, you should be able to replace it fairly easily.

Microwave Malfunction FAQ

What happens if the microwave is turned on with nothing inside?

If nothing is in the microwave when it is running, there is nothing to absorb the microwaves that are generated by the device. These microwaves are used to cook the food in the microwave.

With nothing in there to absorb those waves, the microwave could be damaged.

How do I know if my microwave is bad?

If you notice food cooking more slowly or not at all, your microwave could be going bad. Test it by cooking a cup of water for two minutes.

The cup and water should come out very hot. If it doesn't, something is wrong with the microwave.

What is the average life expectancy of a microwave?

The life expectancy of microwaves varies by model but on average, you can expect most microwaves to last seven to eight years before they need to be replaced.

Can a faulty microwave cause a fire?

A malfunctioning microwave is a serious hazard. The National Fire Protection Association in the U.S. estimates that around four percent of house fires related to cooking activities are started by microwaves every year.

Is it worth it to fix a microwave?

Compared to the cost of a new stove or another household appliance, microwaves are relatively inexpensive. It can be more time-consuming and frustrating to fix a microwave than it is worth.

As a general rule, you should perhaps try to fix a microwave if it is less than five years old and especially if it is still under warranty. But if the microwave is older than this, you should probably replace it because other things could start to go wrong with it after you fix the first problem.