If your microwave runs for a few seconds and stops, then you should check for these 5 possible causes:
1. Faulty door switches
There are door switches in a microwave which must be sealed tightly for the microwave to operate properly. If the microwave runs for a few seconds and then shuts off, the door switch might be defective or loose. Sometimes arching or overheating of door switches stops microwave from running efficiently. Some microwaves have a seal or gasket around the door. If the seal or gasket is broken, microwave shuts down. If your microwave is giving you such trouble call a professional for microwave repair.

LONYE SZM-V16-FD-63 Microwave Oven Door Micro Switch
Microwave Oven Door Switch replacementCommonly found in microwave ovens, this switch will close the circuit once the button is depressed. This switch may be used in many other appliance
Here are some of the other recommended microwave door switches that you can replace yourself:
- LONYE W10727360 & W10269458 & W10269460 Microwave Switch Replacement for Whirlpool Microwave SZM-V16-FC-61 SZM-V16-FC-62 SZM-V16-FC-63
- KW3A Microwave Oven Door Switch 16A 125/250V Door Interloc(Normally Open & 3 Insert Foot)
- Microwave Door Switch SZM-V16-FA-63 by Podoy Compatible with LG GE Starion WB24X829 3B73362F PS3522738 SZM-V16-FD-63 AP2024337
2. Defective touch-pad or control panel
Some microwave models have knobs and dials while others have touch-pads. Microwaves with touch-pads are technological advanced but sensitive compared to the ones with knobs. So if your microwave stops suddenly then there might be a short in the touch-pad control panel.

GE WB56X10822 Genuine OEM Control Panel Assembly
for GE MicrowavesGE Appliances WB56X10822 Microwave Control Panel Assembly houses the selection buttons and display for the microwave
Our other recommended replacements:
3. Malfunctioning voltage transformer
There is a high voltage transformer in a microwave that produces high voltage to charge the magnetron. Upon charging the magnetron emits radio-waves which travels through the wave guide and enter the food area to cook or heat your food. If the microwave runs for a few seconds and stops, the high voltage transformer might have got a sudden short in its circuit. Call a professional for microwave repair.

LG Electronics 6170W1D052Z LG LG-6170W1D052Z Transformer
genuine OEM part manufactured to exact specificationsReplacement LG brand Microwave High Voltage Transformer sends power to the magnetron and capacitor for heating the contents of Microwave
Our other recommended replacements:
- LG Electronics 6170W1D052Z Microwave Oven High Vol 5304479021 Microwave High-Voltage Transformer Genuine Original Equipment Manufacturer (OEM) Part
- Samsung DE26-00126B High Voltage Transformer
4. Faulty cooling fan
There is a fan inside microwave that runs to keep magnetron and other circuitry items cool. So if the microwave starts but the fan does not turn on, it may stop automatically for safety reason.

Lg EAU42744409 Microwave Cooling Fan
genuine OEM part manufactured to exact specificationsBecause high-voltage capacitors in a microwave can retain a lethal electrical charge even when the microwave is unplugged
5. Clogged vent
Microwave also has an air vent to keep it cool. If this vent gets clogged with grease and dust, the microwave will not operate properly. Microwave will shut down automatically for safety reason. So clean the vent with a brush to prevent this problem.
Other reasons that your my microwave runs for a few seconds and stops may be burned internal fuse or defective diodes or faulty capacitors. Call a professional for diagnose and problem resolution for your microwave
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We discovered when our electricity box was replaced that the microwave and oven plug had been badly wired. The electrician had shortened some of the wires to force it into the plug. Once this was corrected the microwave started functioning normally. The oven which also started stopping after 20 mins , was back to normal.
In my case, it’s because the microwave was put in Demo mode.
5 possible causes for one symptom = new appliance.
Diagnosis by trial-and-error is not a recipe for success.
Unless you happen to have all the potential parts on hand + the time to swap them out, this symptom is, in a practice sense, not fixable.
Our microwave door won’t always close properly so that the microwave will run. We’ve had it repaired once before and the repairman tightened something…but we don’t know what!
It’s only a few yrs old and shouldn’t “not work”! It’s $100 or more for a repairman to come out….what could we tell a handyman to do or do ourselves to get it to stay tightly shut ALL the time and not just sometimes.
My microwave comes on for split second and instantly cuts off. Is it worth a repair call