Microwave Sparking or Arcing Inside
Likely causes
- ✓Metal or foil left inside the microwave
- ✓Worn or damaged waveguide cover
- ✓Food debris burning on the guide cover or interior wall
- ✓Damaged interior paint exposing metal underneath
- ✓Failing magnetron
Stop running the microwave as soon as you see sparking. The most common and least serious cause is a damaged waveguide cover — the small panel on the interior wall that protects the microwave-generating components — which gets pitted by food splatters over time and starts arcing. It’s an inexpensive part, but it needs replacing before the unit runs again.
Sparking can also come from chipped interior paint exposing bare metal, or in less common cases, a failing magnetron. Because microwaves hold high-voltage charge even when unplugged, we don’t recommend opening the unit yourself — our technicians handle diagnosis and repair safely, and will tell you plainly if the unit isn’t worth repairing.
This is one of the issues covered under our Microwave Repair service.