Microwave emits sparks or arcing inside the cavity during cooking.

Safety first: Stop the microwave immediately by opening the door or pressing Stop. Disconnect power before inspection.

• Step 1 – Remove metal objects: Ensure no metal utensils, twist ties, or foil are inside. Use only microwave-safe cookware.
• Step 2 – Inspect waveguide cover: Locate the mica or plastic waveguide cover on the side or top wall. If it is burned, cracked, or has holes, it must be replaced.
• Step 3 – Clean cavity: Thoroughly clean the interior with mild detergent and water, removing all grease and food splatter, especially near the waveguide cover.
• Step 4 – Touch-up paint: If small rust spots or chipped paint are present, sand lightly and apply microwave-safe cavity touch-up paint per Thermador recommendations.
• Step 5 – Replace waveguide cover: Install a new Thermador-compatible waveguide cover if damaged.

Warning: Do not operate the microwave with a missing or damaged waveguide cover.