Microwave Sparking or Arcing

If your microwave is sparking or arcing, the problem could be caused by a damaged waveguide cover, metal inside the microwave, a faulty rack, or a failing high-voltage component. Before replacing any parts, inspect the most common causes listed below.

Safety Notice: If you see sparks, flashes, or arcing inside the microwave, stop the appliance immediately and unplug it. Do not continue operating the microwave until the source of the problem has been identified and corrected.

Possible Causes

  • Damaged waveguide cover
  • Metal object or cookware inside the microwave
  • Food splatter or grease buildup
  • Damaged rack or metal support (select models)
  • Chipped or damaged interior cavity coating
  • Failed stirrer cover or stirrer motor
  • Failing high-voltage diode
  • Defective magnetron

1. Damaged Waveguide Cover

Most Common Solution

The waveguide cover protects the microwave's waveguide from grease and food particles. If it becomes burnt, cracked, or heavily contaminated, it can cause sparking or arcing inside the microwave.

What to do:

  • Unplug the microwave.
  • Inspect the waveguide cover for burns, cracks, or discoloration.
  • Replace the cover if it is damaged.
  • Clean the surrounding area before installing the new cover.

2. Metal Object or Cookware

Metal utensils, aluminum foil, twist ties, or cookware with metallic trim can cause sparks inside the microwave.

What to do:

  • Remove all metal objects from the microwave.
  • Use only microwave-safe cookware.
  • Avoid using containers with metallic decorations or trim.

3. Food Splatter or Grease Buildup

Burnt food residue and grease can carbonize over time, creating hot spots that lead to sparking.

What to do:

  • Clean the entire interior of the microwave.
  • Remove any burnt food residue.
  • Wipe the ceiling, walls, floor, and door thoroughly.

4. Rack or Metal Support (Select Models)

Some microwave models include a removable metal rack for convection cooking. If the rack is installed incorrectly or damaged, it may cause arcing.

What to do:

  • Verify the rack is installed according to the manufacturer's instructions.
  • Remove the rack if it is not needed.
  • Replace the rack if it is bent or damaged.

5. Interior Cavity Coating

If the protective coating inside the microwave cavity is chipped or damaged, exposed metal can create sparks during operation.

What to do:

  • Inspect the interior walls for chipped paint or exposed metal.
  • Minor damage may be repairable using microwave cavity touch-up paint designed for appliance interiors.
  • Replace the microwave if the damage is severe or widespread.

6. Stirrer Cover or Stirrer Motor

Some microwave models use a stirrer cover and motor to distribute microwave energy evenly. Damage to these components can lead to arcing.

What to do:

  • Inspect the stirrer cover for burns or cracks.
  • Check the stirrer motor for proper operation.
  • Replace any damaged components.

7. High-Voltage Diode

A failing high-voltage diode can contribute to abnormal microwave operation and may be accompanied by sparking or unusual electrical noises.

What to do:

  • Disconnect power to the microwave.
  • Test the diode using the appropriate test equipment.
  • Replace the diode if it is defective.

8. Magnetron

A failing magnetron can sometimes produce internal arcing, unusual noises, or reduced heating performance.

What to do:

  • Inspect the magnetron for visible damage or signs of overheating.
  • Replace the magnetron if it has failed. Professional installation is recommended.

Need Help Finding the Correct Part?

If you need help identifying the correct replacement part, send us your complete microwave model number and a clear photo of the appliance identification label before placing your order. Our team will verify compatibility and help ensure you receive the correct replacement part the first time.