Why Is My Microwave Buzzing? 5 Causes and Solutions

Your microwave is probably one of the most frequently used appliances in your kitchen, so if you suddenly find yourself asking, “why is my microwave buzzing,” you may need to call a professional to solve the issue. Before you do, learn about what can cause buzzing in a microwave and how to diagnose the issue.

1. Faulty Magnetron

The most common reason for a buzzing microwave is a faulty magnetron, which is the internal component that generates microwave radiation to heat your food. If you hear a high-pitched buzzing noise only when the microwave is on and heating, this is the most likely underlying cause.

The Solution

You’ll need to call in a small appliance repair company near you to replace the magnetron. It’s technically possible to DIY the replacement, but it can be dangerous, especially if your microwave is hardwired. Even if it isn’t, the repair is easy to mess up, which could cause additional appliance damage.

2. Worn-Out Fan

Your microwave uses a fan to cool the internal components during operation. If the fan wears out or malfunctions from dust buildup or constant use, you may hear a choppy buzzing noise during operation.

The Solution

You can first clean the fan blades to see if that solves the issue. Sometimes, dust accumulates unevenly on them, which can cause imbalance issues that lead to buzzing. If that doesn’t work, call a repair tech to replace the fan.

3. Loose Fasteners

If a screw comes loose in the back of your microwave or somewhere on one of the internal components, it will buzz during operation as the appliance vibrates. This will usually sound like a loud, mechanical buzzing rather than an electrical noise. This could be your problem if you or a repair tech recently removed the backing to assess another issue.

The Solution

If you’re able to find the screw that’s loose, shut the power to the appliance, tighten the screw, and turn the power back on before testing it.

4. Diode Issue

The diode in your microwave is responsible for converting AC power from your home’s electrical system to DC power, which the magnetron uses to generate electromagnetic waves. A faulty diode can create a low, muffled buzzing noise during operation. If you notice that kind of buzzing coupled with your food not heating, this could be the issue.

The Solution

You’ll need to have a microwave repair specialist come to replace the diode.

5. Electrical Malfunction

The most dangerous issue that could cause your microwave to buzz is an electrical malfunction, which could stem from damaged internal components, damaged wires behind your walls, or a hidden leak. If you hear buzzing when your microwave is not heating, it could be arcing, which means you have an electrical problem.

The Solution

Immediately shut the power to your microwave using your breaker box and call an electrician in. Arcing could lead to a house fire, so this is considered an emergency situation. Have your electrician confirm if there’s a problem behind your walls. If there isn’t, replace your microwave, as it probably has an internal electrical issue.

When to Call a Pro

You can try searching for loose fasteners and cleaning the blades on the cooling fan to try to fix the buzzing issue, but if that doesn’t work, you should call in an appliance repair specialist. All of the other possible underlying issues require replacing or repairing internal components, and it’s best to leave the work to an experienced pro.