Why Is My Microwave Buzzing? 5 Causes and Solutions

1. Faulty Magnetron

One of the main culprits behind a buzzing sound in a microwave is a damaged magnetron—the part responsible for creating the energy that heats your food. If the noise happens specifically while the appliance is actively warming something, the issue is likely coming from this component.

The Solution

Replacing a magnetron isn’t something to take lightly. While it might seem doable on your own, the process carries risks, especially if the microwave is hardwired into your home. A safer bet is to contact a local appliance repair service, since a small mistake during the fix could lead to bigger problems with the unit.

2. Worn-Out Fan

Microwaves rely on an internal fan to help regulate temperature while running. Over time, heavy use or a buildup of dust can cause that fan to wear down or stop working properly, often resulting in a rough, inconsistent buzzing sound when the appliance is in use.

The Solution

Start by giving the fan blades a thorough cleaning—uneven dust buildup can throw them off balance and cause unwanted noise. If the buzzing doesn’t stop after cleaning, it’s probably time to bring in a technician to install a new fan.

3. Loose Fasteners

A loud mechanical buzzing—different from the typical hum of electricity—might point to a loose screw inside the microwave. Vibration during use can cause that kind of noise, especially if the back panel or interior parts were recently removed for inspection or repair.

The Solution

If you locate a loose screw, make sure to disconnect the microwave from power first. Once it’s safely off, tighten the screw securely, then restore power and check if the noise is gone.

4. Diode Issue

Inside your microwave, there’s a component that shifts the incoming electrical current into a form the magnetron can use to produce heat. When this part—called a diode—stops working properly, you might hear a soft, dull buzzing while the appliance runs. If that sound shows up along with poor heating, the diode could be to blame.

The Solution

To fix this issue, it’s best to have a professional who handles microwave repairs install a new diode.

5. Electrical Malfunction

One of the riskiest causes of buzzing in a microwave is an electrical fault. This might happen because of broken parts inside the unit, damaged wiring inside your walls, or even a concealed electrical leak. If the microwave buzzes but doesn’t warm your food, it could be due to electrical arcing, signaling a serious issue.

The Solution

If you suspect electrical arcing, cut the power to your microwave right away at the circuit breaker and contact a qualified electrician. This situation can be very dangerous and might even cause a fire. The electrician should check for any wiring problems within your walls. If everything checks out, it’s likely your microwave itself has a serious electrical fault and needs to be replaced.

When to Call a Pro

To address the buzzing sound, you might want to check for any loose screws and clean the cooling fan blades first. If those steps don’t resolve the problem, it’s wise to reach out to a professional technician. Since most other causes involve fixing or swapping internal parts, it’s safer to trust an expert with the repairs.