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Fix a microwave that makes noise

We'll identify the noise by type—metal in cavity, turntable, waveguide cover, or fan—then fix it or tell you when to call a pro.

Troubleshooting · Home appliances
15–30 min
What you'll need
  • Level (to check if the microwave is level)
  • Vacuum with brush attachment (for external vents)
  • Replacement waveguide cover (if damaged)
Step 1 of 7

Quick triage — pick your path

Quick triage — pick your path

Choose the option that matches what you see. You can jump straight to that section.

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Steps

Goal: Confirm the noise is unusual, identify the type, then fix metal in cavity, turntable, waveguide cover, or know when to call a pro.

  • Listen to the microwave. Normal: soft hum from the magnetron and transformer, fan, turntable motor. Unusual: loud humming, rattling, grinding, or popping and arcing.
  • Symptom confirmed: Noise is unusual—proceed to Identify the type of noise.
  • No problem: Soft hum and turntable—normal operation. No action needed.

Identify the type of noise

Goal: Narrow the cause by noise type.

  • Run the microwave empty for 10 seconds and note the sound.
  • Humming or buzzing: Magnetron, transformer, or fan. Loud or changing hum—call a pro. See When to get help.
  • Rattling: Turntable plate, support, or stirrer. See Turntable path.
  • Grinding: Turntable motor or fan motor. Call a pro.
  • Popping or arcing: Metal in cavity or damaged waveguide cover. See Metal and waveguide.

Metal and waveguide

Goal: Stop popping and arcing from metal in the cavity or a damaged waveguide cover.

  • Unplug the microwave. Open the door and remove any metal objects, foil, or containers with metal trim. Confirm the cavity is empty of metal.
  • Inspect the waveguide cover (plastic or mica panel, usually on the right side or top of the cavity). If it is burned, warped, or damaged, replace it with an exact match. Do not run the microwave with a damaged cover.
  • Good: Cavity clear and cover intact or replaced. Popping stops when you test.
  • Bad: Still arcing after clearing metal and replacing the cover—call a pro.

Turntable path

Goal: Fix rattling from the turntable plate, support, or stirrer.

  • Unplug the microwave. Remove the turntable plate and the turntable support ring. Inspect for cracks or chips. Confirm the support sits correctly on the drive hub. Reinstall the plate so it rotates freely.
  • Check if the microwave is level. Adjust the feet or mounting bracket so the unit does not rock.
  • If your model has a stirrer (plastic blade in the top of the cavity), check that it is intact and unobstructed. If loose or damaged and you cannot access it safely, call a pro.
  • Good: Plate and support intact, unit level. Rattling stops when you test.
  • Bad: Grinding from the turntable motor—call a pro. Motor replacement is internal.

When to get help

Call an appliance technician if:

  • You hear loud humming or grinding from inside (magnetron or fan).
  • The microwave arcs or sparks and you have cleared metal and replaced the waveguide cover.
  • You have fixed the turntable and waveguide and the noise continues.
  • You are not comfortable with appliance repair.

Microwaves contain high voltage. Never open the cabinet with the unit plugged in.

Verification

  • The microwave makes normal sounds (soft hum, turntable) or the unusual noise is resolved.
  • No metal or foil in the cavity; waveguide cover is intact.
  • Turntable plate and support are seated correctly; unit is level.
  • No popping, arcing, or grinding.

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Confirm symptom Verify the noise is unusual—not normal hum or turntable.
  2. Identify type Note the noise type—humming, rattling, grinding, or popping—to narrow the cause.
  3. Metal and waveguide Remove metal from cavity; check the waveguide cover for damage.
  4. Turntable and leveling Check the turntable plate and support; level the microwave.
  5. Call a pro Loud humming, grinding, arcing, or repeated noise—call an appliance technician.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • Type of noise (humming, rattling, grinding, popping)
  • Whether metal or foil was in the cavity
  • Condition of turntable plate and support
  • Condition of waveguide cover
  • Steps already tried

Is the noise unusual?

Normal: soft hum from magnetron and transformer, fan, turntable. Unusual: loud humming, rattling, grinding, or popping and arcing.

Listen to the microwave. Symptom confirmed: loud humming, rattling, grinding, or popping—proceed to identify type. No problem: soft hum and turntable—normal operation.

Symptom confirmed No problem

You can change your answer later.

No action needed

The microwave makes normal sounds. No further action required.

Done

Is it popping or arcing?

Popping or arcing: metal in cavity or damaged waveguide. Rattling: turntable. Humming or grinding: magnetron or fan.

Run the microwave empty for 10 seconds. Popping or arcing: metal in cavity or damaged waveguide cover—proceed to metal and waveguide. No: check if rattling or humming.

Yes No

You can change your answer later.

Is it rattling?

Rattling: turntable or stirrer. Humming or grinding: magnetron or fan—call a pro.

Rattling: turntable plate, support, or stirrer—see Turntable path. Loud humming or grinding: magnetron or fan—call a pro. See When to get help.

Yes No (humming or grinding)

You can change your answer later.

Metal in cavity or damaged waveguide?

Metal and foil cause arcing. A damaged waveguide cover can also cause arcing.

Unplug the microwave. Remove any metal, foil, or foil-lined containers from the cavity. Inspect the waveguide cover for burns or damage. Replace if damaged. Good: cavity clear and cover intact—test. Bad: still arcing—call a pro.
Question

Metal removed and waveguide checked?

Done

Turntable and leveling

Loose or cracked turntable plate, misaligned support, or unlevel unit causes rattling.

Unplug the microwave. Check the turntable support and plate for cracks or looseness. Reinstall correctly. Level the microwave. Good: plate and support intact, unit level—test. Bad: grinding from turntable motor—call a pro.
Question

Turntable and leveling checked?

Done

Loud humming or grinding — call a pro

Loud humming or grinding from inside usually means magnetron or fan. Internal repair requires a technician.

Loud humming or grinding from inside the cabinet usually means the magnetron or fan motor. Microwaves contain high voltage. Do not open the cabinet. Call an appliance technician.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why would a microwave hum or buzz loudly?
A soft hum from the magnetron and transformer is normal. Loud humming or buzzing can mean a loose magnetron mount, failing fan motor, or transformer issue. Internal repairs require a technician—microwaves contain high voltage.
What causes rattling in a microwave?
Rattling often comes from a loose or cracked turntable plate, a misaligned turntable support, or objects in the cavity. Check the turntable first. Grinding from the turntable motor means the motor is failing—call a pro.
When should I call a technician for microwave noise?
Call a pro if you hear loud humming or grinding from inside (magnetron or fan), if the microwave arcs or sparks, if you have fixed the turntable and waveguide and the noise continues, or if you are not comfortable with appliance repair. Never open the cabinet with the microwave plugged in.

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