Microwave Sparking – 6 Common Reasons and Fix It

Is your microwave sparking while cooking? This incident can baffle you, considering sparking can lead to a fire. It also makes you wonder whether is a sparking microwave dangerous. However, there is nothing to be alarmed about.

So, why is my microwave sparking? Microwave sparking and burning smell can happen for many reasons, and the causes are mostly easy to resolve. In some cases, microwave sparking occurs when there is a piece of metal fragments.

On the other hand, the malfunctioning diode and magnetron are responsible for microwave sparking and burning smells. Therefore, both causes are solvable.

So, let’s find out everything about why your microwave is sparking. Thus, you will also get a microwave spark troubleshooting guideline.

Is A Sparking Microwave Dangerous?

A microwave sparking is a common incident and doesn’t usually pose any threat like catching fire accidents. Usually, the sparking inside the microwave occurs due to the build-up of food debris and grease.

On the other hand, it also happens when there are metal, aluminum, or tin fragments in the microwave. If you neglect the microwave sparking, it may lead to a fire explosion later on.

Moreover, microwave sparking can take place when some of the essential microwave compartments such as rack, waveguide cover, magnetron, or diode are damaged.

In addition, sparking also indicates that your microwave has gone bad, and you may need to get a new microwave oven.

As microwave sparking is quite uncertain, it can make you panic and worry too much. However, rather than panic, you must find the source of the microwave sparking and resolve it.

Why Is My Microwave Sparking – How To Fix It

If you notice sparking in your microwave, it is crucial to take appropriate action to resolve the issue.

Here are a few common reasons why your microwave is sparking:

Reason 1: Metal Fragments In The Microwave

You should never put tinfoil, aluminum, or metal inside the microwave, even by mistake. These components cause sparking in the microwave and damage it.

So, did you put any metal components in the microwave? Is the tray you put inside microwave-safe and has no metal? If you did put metal items in the microwave, no wonder microwave is sparking all of a sudden.

Before you proceed to the more complex and technical reasons for microwave sparking, start by identifying the simplest cause and resolve it.

s a sparking microwave dangerous

How To Fix:

Here’s what to do if there are metal fragments inside the microwave:

  • Disconnect the microwave and open it.
  • Clean inside the microwave thoroughly using vinegar, lemon, soap, and a washcloth.
  • Rub out all the nasty specks of dirt and grease. The metal fragments will rub out along with other dirt.
  • Wipe again to make sure no metal fragments remain.

Reason 2: Rusty Microwave Racks

If you own a big microwave with racks in it, the worn-out racks may be causing the microwave to spark while cooking. The microwave racks are metal components to withstand high heat while holding the food tray. On top of that, the metal racks are electro-plated with plastic to prevent sparking.

However, using the racks for a long time without proper care and cleaning can make the protective plastic cover wear away. As a result, when the metal of the rack is exposed, it will ignite sparks.

How To Fix:

Here’s what to do to fix the worn microwave racks:

  • Take out the racks from the microwave and look for any visible sign of metal exposure.
  • If the rack is not clean and wash it and then inspect it again.
  • Replace the microwave rack if it is worn out too much, or try electro-plating it again.

If the racks are fine, proceed to the next reason and follow its guideline.

Reason 3: Damaged Waveguide Cover

Damaged Waveguide Cover

A dirty or broken waveguide is likely to create sparks in the microwave while cooking. A waveguide cover in the microwave is used for transferring and distributing power energy inside the microwave in the heat form. It looks like a small white rectangle panel on the side of the microwave.

As waveguide is utilized by the microwave every time, it gets dirty and wears away easily. Although we clean up the microwave when it gets greasy, we end up neglecting the waveguide as it is mostly unnoticeable.

When the waveguide becomes dirty, the oily grease and food debris on it can cause sparks. Well, this occurs because the power rushing in the waveguide cover from the magnetron burns the food particle, dirt, and grease. At first, the little sparkings will seem harmless.

However, prolonged and neglected sparking will seriously damage and even break the waveguide cover. If the waveguide cover is broken and left alone, it will eventually damage the microwave for good.

How To Fix:

I know you don’t want to get a new microwave just for being careless. So, follow the steps below to fix the microwave sparking and burning smell by cleaning or replacing the waveguide cover:

  • Unplug the microwave to clean the waveguide panel thoroughly.
  • Unscrew the waveguide panel from the microwave and clean it.
  • Dry the waveguide cover and inspect for any visible damages.
  • If the waveguide panel is beyond saving, replace it.
  • Buy the same model waveguide cover and screw it in place.

In case neither of the two reasons seems to be the cause, go to the next guideline.

Reason 4: Broken or Faulty Diode

Faulty Diode

The diode in the microwave ensures supplying high voltage electricity to power the magnetron. Afterward, that magnetron uses a waveguide to distribute the power through heat energy to cook food fast.

The microwave sparking and burning smell, not heating food properly or evenly, is the indication of a faulty diode.

The diode of the microwave can fuse, be short, break, or wear out over a long usage period. And if the diode is faulty, it needs replacing without any exception.

How To Fix:

Follow the steps below with precautions to find and replace the diode:

  • Switch Off and disconnect the microwave’s power cord.
  • Remove the access panel of the microwave (it’s either at the top or back).
  • Get a visual inside the cabinet next to the magnetron (the small cylindrical part is the diode).
  • Disconnect the capacitor from it with caution (it may contain an excessive amount of electricity).
  • Test the diode’s continuity using a multimeter by holding the leads with each end of the diode (red lead goes to the positive terminal and black lead to the negative terminal).
  • If the multimeter shows positive continuity, the diode is fine.
  • If the continuity is negative, replace the diode right away.
  • Thus, screw all parts back in their place carefully.

Reason 5: Faulty Magnetron

The magnetron of the microwave will hardly cause sparking for no reason. It is one of the primary components responsible for producing heat.

But like all other components, the magnetron will wear out, malfunction, and get damaged due to voltage overload. As a result, you will experience the microwave sparking and burning smell.

In addition, when the magnetron is faulty, the food will not heat up properly, and the microwave will make a humming noise. Besides, if the condition of the magnetron gets worse, you will also be able to see the sparking.

Faulty Magnetron

How To Fix:

Here’s how to locate and replace a faulty magnetron in the microwave:

  • Unplug the microwave from the power source.
  • Unscrew the top cover to locate the magnetron in the microwave.
  • Discharge the capacitor to ensure there’s no excess electricity flowing through the components.
  • Remove the magnetron by unscrewing the bolts and then test its continuity.
  • Utilize a multimeter (set it to ohm) to ensure the magnetron is broken and has no continuity.
  • If the ohm read is below 1, it means the magnetron has continuity.
  • Program the multimeter to test the highest resistance and connect the leads to the magnetrons casings/wires/connectors again.
  • If the reading is not OL, the magnetron is not functioning and is defective.
  • Purchase a new magnetron of the same model and replace the old one.

Reason 6: Worn-out Paint Inside the Microwave Cavity

Damaged or worn-out paint inside the microwave cavity can expose metal surfaces, leading to sparking.

The best way to avoid this is to periodically inspect the paint inside the microwave cavity for any signs of wear or damage.

How To Fix:

  • Unplug your microwave and wait for it to cool down.
  • Carefully examine the interior walls of the microwave cavity for any chipped or peeling paint.
  • If you notice any areas where the metal is exposed, consider repainting or replacing the microwave cavity.
  • Contact the manufacturer or consult with a professional technician for guidance on repainting or replacing the cavity.

Note: Always ensure safety first when repairing a microwave because the sparking can also occur elsewhere in the microwave where it’s not detectable. Also, only purchase genuine manufacturer microwave oven parts with the same model number.

How To Prevent Your Microwave From Sparking?

Sparking in the microwave is a common issue that can be caused by a variety of factors, including metal, dirty or damaged components, and the use of non-microwave-safe utensils etc.

To prevent microwave sparking, please follow these steps:

Regular Maintenance

Regular maintenance is essential for preventing sparking in a microwave. It is recommended to clean the interior of the microwave after each use to remove any food particles or debris that may cause sparking.

Additionally, it is important to inspect the microwave’s components, such as the turntable and waveguide cover, for any signs of damage or wear and tear.

If any components are damaged, they should be replaced immediately to prevent further damage to the microwave.

Proper Use of Foil and Metal

Improper use of foil and metal is a common reason for sparking in a microwave. To prevent sparking and potential damage to your microwave, it’s important to avoid using aluminum foil or metal utensils inside.

Instead, it would be best if you used microwave-safe containers and covers made of glass, ceramic, or plastic.

Safe Microwave-Compatible Utensils

You should only use utensils that are labeled as microwave-safe. Also, ensure they are made of materials that are designed to withstand the heat and energy of the microwave.

Some examples of microwave-safe utensils include glass, ceramic, and plastic containers, as well as microwave-safe paper towels and wax paper.

So, if you follow these instructions properly, your microwave will not spark anymore.

Why Is My Microwave Sparking Without Metal?

The most common way for a microwave to get sparking is by having metal fragments inside while cooking.

However, microwaves can cause sparking without metals. In most cases, the reasons are underlying and need immediate solving or replacement.

Hence, here is why your microwave is sparking without metal:

  • Chipped microwave racks
  • Worn-out microwave paint
  • Defective diode
  • Malfunctioning magnetron
  • Dirty and faulty waveguide panel

As we have already mentioned these reasons previously, you must know how to resolve them and stop the microwave from sparking.


The guide of My Microwave Sparking is now over. I hope I have provided all the information about microwave sparking and burning smell.

Don’t forget to follow the safety rules while using the solutions with steps because electrical appliances can store lethal amounts of electricity.

Thus, hurry up and fix your microwave sparking to bake and cook delicious dishes!

Frequently Asked Questions [FAQs]

How do I fix the microwave from sparking?

Cleaning the microwave inside out and replacing the defective parts with new ones will stop the microwave from sparking.

Is it unsafe to use a microwave that sparks?

Yes. If there are visible big sparks in the microwave, you should immediately stop using it and seek professional help ASAP.

Why is the microwave sparking but no metal?

Microwaves can sometimes spark because there is a build-up of grease and dirt in the waveguide panel, the diode is faulty, or the magnetron is broken.

Why is my microwave suddenly making a popping noise and sparks?

Usually, the build-up of food and grease inside the microwave can create popping sounds and sparks while cooking at high temperatures.

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