Microwave Turns on By Itself – Or Won’t Stop Running

A microwave is now in almost every home. Many people use it as a necessary kitchen item to simplify cooking. Unfortunately, it can be challenging and expensive to repair or replace when it stops functioning correctly.

A microwave could stop functioning correctly for several reasons. This article will review the various reasons and problems associated with why your microwave turns on by itself, and how to fix them.

Safety Warning: Microwaves can develop issues over time, the most prevalent of which is that they turn on by themselves. When this occurs, it immediately poses a risk to public safety and must be remedied straight away. A microwave oven will frequently turn on by itself for the following reasons.

Microwave Turns On When Door Is Open

Several things can cause your microwave to turn on when you open the door, including defective door switches, software errors, and failed internal circuitry.

Below, we will look at a few solutions you can try if your microwave turns on when the door is open.

Faulty Door Switch

If your microwave turns on when you open the door it is most likely a faulty door switch. This interlocking switch plays a role in the flow of power to the microwave and acts as a safety component. If it is faulty it can lead to no power or alternatively continuous power supply.

A faulty switch could open an electrical circuit when the microwave door is closed. This usually results in the microwave light or fan switching on too. It is possible to fix this with a reset, so try this before going to the next step of replacing the faulty switch.

Soft Reset

There should be a RESET button on the display board of the microwave. If your microwave lacks a RESET button, you might try pressing the OFF or CLEAR button for three to five seconds. When the device resets to factory default settings, it will beep and display a message on the screen. If this doesn’t work, it’s best to consult the microwave’s user guide and follow the instructions provided.

Hard Reset

Hard reset the machine by removing the plug and leaving the appliance alone for 30 to 60 minutes to allow the microwave’s processors and circuits’ electricity to dissipate. Then, plug in the microwave again, and turn it on. This process should resolve the issue if a software bug is a cause.

Check out How to Silence A Microwave Beep helping you set your microwave to silent mode.

Replacing a Faulty Door Switch

Replace the damaged door switch. If a broken door switch causes the microwave to turn on whenever you open it, merely swap it out for a new one. Replacing a microwave door switch is only really suitable for people with reasonable competence in DIY. Watch the short video below and see if you feel this task is within your capability. If not, call a professional for assistance. Of course, if the manufacturer’s warranty covers the microwave, you can call for assistance.

Important Safety: before removing any componentry or coverings on your microwave oven, be sure to unplug the microwave oven and discharge the capacitor.

GE Microwave Door Replace Switch, Upper & Lower #WB24X829

Call a Professional

If restarting the microwave and replacing the door switch didn’t fix the problem, it’s possible that some internal components are damaged. The microwave might switch on when the door opens if the wiring is faulty or water has entered the motor. In this situation, it’s preferable to call a professional skilled in this area to fix your microwave.

Microwave Power Turns On When Door Closes

If a microwave turns on when its door closes, most probably, the power isn’t shut off because the control board isn’t providing the proper signals. It might also imply that one of the door switches is malfunctioning or broken. The following troubleshooting tips may help determine the problem. 

The microwave control panel consists of both the control board and the touch panel. A fault within either of these components could lead to the microwave switching itself on when the door is closed.

Check Control Board

The control board is most likely at fault if the microwave won’t stop working after you close the door. If your microwave turns off only when the door opens, it suggests that either the door switch is not sending the correct signal or the control board is not receiving the signal. Either way, you may need to change the control board. 

Safety Warning: Attempting to repair the control board, or touch panel required technical knowledge due to the electrical risks. Seek advice from a technician.

Testing Microwave Control Board

You can test the control board for faults using the following steps:

1. Ensure the microwave is still receiving power.
2. Remove the microwave cabinet to access it. Look for the control board. The control panel is typically located directly beneath the keypad.
3. Look for burns or signs of damage on the control board. Replace the control board if you can notice any signs of damage.
4. Use a multimeter to test the board if you can’t see any damage. Check for continuity by setting your multimeter to Rx1 and placing the probes on the relay’s output terminals.
5. Replace the control board if the test reveals that there is no continuity.

Change the Interlock Switch

When the microwave door closes, an interlocking switch is activated, and this allows the microwave to receive power. If this switch is faulty it can cause the microwave to receive no power at all or continual power. Continual power can lead to switching the microwave on when you close the door.

The interlock switch is typically next to the control panel, near the door and the cabinet converges at the touchpad. Despite being more difficult to locate, the switch is simpler to replace than the control board. You can refer to the instruction provided earlier in this article.

Faulty Touch Panel – Buttons Activating On Their Own

If you have a faulty touch panel (touchpad), you may find the microwave power switches on when the door is closed.

This will be due to a damaged control board not sending the correct signals to the various microwave functions.

Or it could be a damaged touchpad membrane leading to jammed or unresponsive control buttons.

Alterations to Membranes

The membrane switch may be the issue if you can’t find the exact cause. It has a conductive coating that, with continued usage, may degrade. To troubleshoot this component, ensure the microwave is unplugged, and remove the cabinet. Check the membrane switch using a multimeter. You should receive several ohms of resistance from it. If not, it has to be modified.

The Button Panel

Your microwave’s touch controls might not function, but if the display lights are still on, there is probably an issue with the control board. The membrane switch receives power from the control board. Your oven’s buttons won’t operate well without it. You should let a professional replace this part, as it is difficult to repair.

Microwave Fan Won’t Turn Off When Door Closed

Several factors can cause a microwave to malfunction. Defective filters sometimes stop the oven from working, while broken thermostats keep the microwave fan running. There are numerous causes for a microwave fan not to turn off when it should, including the following.

Ineffective Filters

Dirt and dust can accumulate over time and obstruct grease and air filters. Check these filters if your microwave’s vent fan won’t shut off. You can clean or replace them if necessary.

Damper Assembly

When the damper assembly fails to perform as intended, the microwave vent fan stops operating correctly. Inspect the damper for weakness, cracking, or damage.

Malfunctioning Thermostat

The exhaust fan of the microwave won’t shut off if the thermostat is malfunctioning. Instead of repairing a broken thermostat, you should consider purchasing a new one.

Malfunctioning Fan Motor

The microwave’s fan motor may malfunction occasionally, so it’s important to inspect it regularly. 

Microwave Keeps Running After Timer Stops

If the heating is functioning fine but the screen is blank, the controller or its power source probably has a problem. Here is what to do to fix the issue:

• A power outage or an alpha wave could have caused the controller to glitch. So, check if there is a power outage or voltage drop.
• Check the screen and the power supply for loose connections. Additionally, check the solder joints on the controller board.
• Although unlikely because it requires considerable force, if the oven received physical damage, the screen could have broken. The door seals, in this instance, could sustain greater damage, which can interfere with the timer.

Microwave Light Stays On When Door Is Closed

If you close the door of the microwave after you’ve finished reheating a meal, the microwave light may turn on, but this shouldn’t happen if the microwave isn’t in use. In this case, you should: 

• Check whether the door latch is damaged. 
• The door’s interlock switch may be to blame for the issue. Using a multimeter, check its continuity. You might find a broken door’s interlock switch and need to replace it.

Solved: Microwave Turns On By Itself

If your microwave turns on by itself, you’ll need to act quickly to end the issue and ensure that the microwave lasts as long as possible. Fixing these issues will also give you peace of mind that you can leave the house safely. 

Unplugging your microwave and waiting for around 20 minutes before plugging it back in is usually the best way to reset it. You can use the steps outlined in this guide before purchasing a new microwave if a reset doesn’t solve the issue.