Microwave emits a burning smell, smoke, or visible arcing (sparks) inside the cavity.

Immediate safety warning: Stop the microwave immediately by pressing STOP or opening the door. Unplug the unit. Do not continue to use the microwave until the cause is identified and corrected.

Step-by-step checks:

• 1. Remove metal objects: Ensure no metal utensils, foil, or metal-trimmed dishes are in the cavity.
• 2. Clean thoroughly: Once cool, clean the interior with a mild detergent and water, removing all grease and burnt food, especially near the waveguide cover (usually a small rectangular panel on the side or top wall).
• 3. Inspect waveguide cover: Check the mica or plastic waveguide cover for burn marks, holes, or cracks. Replace if damaged.
• 4. Check cavity paint: Look for chipped or burned paint exposing bare metal. Small areas can sometimes be touched up with microwave-safe cavity paint; extensive damage requires professional evaluation.
• 5. Test carefully: After cleaning and replacing the waveguide cover, run a short test with a cup of water. If arcing or burning smell persists, discontinue use and contact a technician.