Sparks inside a microwave are alarming, but the cause is often simple, such as metal in the cavity or food residue. The important thing is to stop the microwave right away.
Call (539) 281-3311All troubleshooting guidesWhat to do right away
- Stop the microwave and unplug it.
- Remove everything from inside once it has cooled.
- Look for metal such as foil, a fork, twist ties or a dish with a gold or silver rim.
- Look for burn marks or damaged paint on the inside walls.
- Check the small cover on the right side wall, called the waveguide cover.
Common causes
- Metal in the cavity, including foil, utensils and plates with metallic trim.
- A burnt or damaged waveguide cover, which is often a thin sheet of material on the side wall.
- Food splatter or grease burnt on to the walls.
- Worn or flaking paint inside the cavity.
- Running the microwave with very little or nothing inside.
When to stop using it and call
- It sparks with nothing metal inside.
- You see burnt marks, a hole or peeling paint inside the cavity.
- There is a burning smell, or it makes loud buzzing.
- The waveguide cover is burnt or damaged and you are unsure how to replace it safely.
Frequently asked questions
Why is my microwave sparking?
The usual causes are metal inside, a damaged waveguide cover or burnt food residue. Remove metal, clean the inside and check the cover.
Is it safe to use a microwave that sparks?
Stop using it until you know the cause. If it sparks with nothing metal inside, it needs checking before you use it again.
Can I fix a microwave myself?
You can clean the inside and replace a damaged waveguide cover on some models. Do not open the casing, because the capacitor can hold a dangerous charge.
Is it worth repairing a microwave?
For a basic countertop microwave, replacement is often cheaper. A built-in or over-the-range unit may be worth repairing. See our repair or replace guide.
Related guides
Microwave still sparking?
Call and tell us what you saw and what was inside. We will tell you what to expect before anyone comes out.
Call (539) 281-3311Written by the ElectricAppliance team, 2351 W Vancouver St, Broken Arrow, OK. Last updated 2026-10-29. This page is general information, not a quote. Prices and timing depend on the appliance, the part and the fault, so call for a diagnosis.