The part(s) or condition(s) listed below for the symptom Microwave turns on by itself are ordered from most likely to least likely to occur. Check or test each item, starting with the items at the top of the page.
First, make sure that the touchpad is working properly. If the touchpad is working properly, the main control board is likely at fault. If the control board is defective, replace it.
Most over-the-range microwaves have a vent fan thermostat that will turn the vent fan on to keep the microwave from overheating. It is normal for the vent fan to come on by itself when cooking on the stovetop under the microwave. The fan will shut off after the microwave cools back down.
A microwave that turns on by itself can be caused by a malfunctioning interlock switch. You can use a multimeter to test the interlock switches to determine if they are functioning appropriately and replace if necessary.
Switch Holder
It’s possible that the touchpad and control panel button circuits are coming into contact with each other intermittently which could cause the microwave to turn on by itself. If this happens, the touchpad and control panel will need to be replaced.
It’s possible that the touchpad button circuits are coming into contact with each other intermittently which could cause the microwave to turn on by itself. If this happens, the touchpad will need to be replaced.
A bent microwave door hinge can cause the door to sag which may inadvertently allow some of the door switches to open and close. This may cause the lights to come on and off intermittently. Inspect both door hinges for damage and replace if necessary.
A microwave that turns on by itself can be caused by a malfunctioning door switch. You can use a multimeter to test the door switches to determine if they are functioning appropriately and replace if necessary.
A microwave that turns on by itself can be caused by a malfunctioning micro switch. You can use a multimeter to test the micro switches to determine if they are functioning appropriately and replace if necessary.