Microwave Turned On By Itself? (here’s why & what to do)

If your microwave turns on by itself, it’s a potentially dangerous situation. A microwave should never be operated with no food inside to absorb those microwaves.

This could cause internal damage to the appliance as well as increase the risk of the microwave catching fire. Which all means you need to do something to fix this problem as soon as possible.

In this article I look at all of the potential reasons why a microwave might turn itself on and offer solutions to those issues.

Safety Notice:

The capacitor in a microwave can hold onto a lethal charge of electricity for up to 48 hours after being disconnected from the power supply.

Which is why I recommend contacting a technician to investigate any component that requires the dismantling of any part of the appliance.

Why Does The Microwave Turn Itself On?

There are several reasons why a microwave might turn itself on which include;

Probable CauseSolution
Faulty Door LatchInspect & clean the door latch and replace if necessary
Stuck Or Defective Door SwitchInspect the door switch and replace if necessary
Faulty Touchpad MembraneInspect the touchpad membrane and replace if needed
Defective Control PanelInspect the control panel and replace if necessary
Defective Heat Sensor Panel Disconnect the microwave’s plug when using the cooker
Defective Control BoardContact a technician

Let’s look at each of these problems in more detail;

Faulty Door Latch

Microwave

Over time the door latch can become dirty and partially clogged with spilled food or dried liquids. The first thing to do is inspect and clean the door latch and latch mechanism.

Then try closing the door securely, this could be all that’s needed to solve this issue. However, if the problem remains, the door latch or mechanism is probably defective and will need to be replaced.

Stuck Or Defective Door Switch

The door switch malfunctioning is one of the most overlooked causes of a microwave turning itself on. The door switch could cause an open circuit which should mean there’s no power running through it. However, in some cases, it could cause the microwave light to come on as well as start the fan.

This will almost certainly be caused by a faulty interlock which will need replacing.

In some cases this can be cleared by performing a reset. There are two types of reset when it comes to microwaves which are;

Soft Reset

To perform a soft reset all you need to do is locate and press the reset button on the touchpad of your appliance. For microwaves that don’t have a reset button, simply press and hold the off button for around 5 to 7 seconds.

Hard Reset

A hard reset involves disconnecting the power supply by removing the plug from the wall socket or flipping the circuit breaker to the off position. You then need to allow all of the electrical charge to dissipate.

Due to the capacitor, this could take up to 48 hours, but you could try leaving the power off for around 1 to 2 hours as this is often long enough for the capacitor to discharge.

If after resetting the microwave, the problem still remains, it’s time to contact a technician to investigate.

Faulty Touchpad Membrane

Samsung microwave

The touchpad membrane is made from two layers: a plastic bottom layer connected to a conductive rubber top layer. The touchpad is operated using the soft touch technique.

Over time the rubber layer can begin to wear out. This breaks the circuit leading to malfunctions. This could go either way, causing the microwave to stop working, or turning itself on whenever a power supply is present.

The membrane will need to be tested for continuity and if found to be defective, it will need to be replaced. This is another job best left to a technician.

Defective Control Panel

The control panel is located directly beneath the touchpad and is connected to the touchpad by a thin membrane. When the touchpad is pressed, the membrane connects to the corresponding area of the control panel and signals the control board of the action required.

If the control panel develops a fault, it could cause the microwave to start on its own. As accessing the control panel involves dismantling parts of the appliance, I recommend contacting a technician to investigate and repair/replace any defective parts.

Defective Heat Sensor Panel 

If your microwave is an over the range model, it will have a heat sensor that is responsive to the heat of your finger. This allows you to operate the appliance using a very light touch.

Unfortunately, this sensitivity to heat can lead to the microwave starting if there is heat being generated below it from the cooker. If this is the case, you will need to get the heat resistance sensor checked and replaced if it proves to be faulty.

However, over the range microwaves have an automatic fan to help prevent the electrical components from overheating when the range or cooker is being used. The built-in thermostat automatically turns the fan on if the appliance is too hot.

The fan will continue to run until the thermostat detects that the appliance has cooled down sufficiently.

Defective Control Board

The control board on a microwave is responsible for managing every function of the appliance. If the microwave is starting by itself, and you’ve checked everything else, all that’s left is the control board.

Sometimes control board malfunctions are just software or electrical glitches and can be solved by performing a reset (see above). However, if the problem remains after performing a reset, it’s likely that the control board will need to be replaced.

Control boards are expensive and delicate components that can easily become damaged. Which is why I recommend getting a technician to investigate and replace the control board if necessary.

SEE ALSO: Flatbed Microwave Vs Turntable – which is better?

Frequently Asked Questions

Can microwaves start by themselves?

A malfunctioning microwave can start by itself under certain conditions. This is potentially dangerous because it could cause the capacitor to burn out or start a fire if the microwave is running with nothing inside it.

What causes a microwave to start up by itself?

If your microwave is starting up by itself, it could be because; the door latch is faulty, the door switch is defective, the touchpad membrane is faulty, the control panel is faulty, the heat sensor panel is defective or the control board is defective.

Why would a microwave fan turn on by itself?

If you own an over the range microwave, it will typically have an automatic fan that will run as soon as the built-in thermostat detects the appliance is getting too hot. This is a safety feature designed to protect electrical components from overheating. The fan will stay running until the temperature has cooled sufficiently.

Leave a Reply

Your email address will not be published. Required fields are marked *