How to Fix / Troubleshooting

Safety first: Stop the microwave immediately and unplug it if you see sparks.

Remove metal objects: Ensure no metal utensils, foil, or dishes with metallic trim are inside.
Inspect waveguide cover: Check for burns, cracks, or holes. A damaged cover must be replaced before further use.
Check cavity coating: Look for chipped enamel exposing bare metal, especially near corners. Small chips can sometimes be touched up with microwave-safe cavity paint by a professional.
Clean thoroughly: Remove all grease and food residue, particularly near the waveguide cover and ceiling.
Test carefully: After cleaning and replacing any damaged cover, test with a cup of water. If arcing recurs, discontinue use and seek professional service.

Warning: Continued operation with arcing can damage the magnetron and pose a fire risk.

Microwave cavity shows sparks (arcing) during operation.

Possible Causes