Visible sparks (arcing) or popping sounds inside the microwave cavity during cooking.

Immediate safety: Press STOP/CLEAR and unplug the microwave as soon as you see sparks. Do not continue cooking.

Steps:

• Remove metal: Take out any metal utensils, foil, or containers not rated for microwave use.
• Clean cavity: Once cool and unplugged, clean the interior thoroughly with mild detergent and water, focusing on areas with heavy splatter. Dry completely.
• Inspect waveguide cover: Check the small cover on the side wall. If it is burned, cracked, or has holes, do not use the microwave until it is replaced.
• Check for chipped paint: Look for bare metal spots where enamel has chipped. Small chips can sometimes be touched up with microwave-safe cavity paint, but larger damage requires professional evaluation.

If arcing continues after cleaning and removing metal, have a technician replace the waveguide cover and inspect the cavity for damage.