Microwave does not heat and may stop with E04; a loud humming or buzzing noise is heard when attempting to cook.
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Possible Causes
How to Fix / Troubleshooting
Safety: Unplug the microwave before inspection. Do not touch internal high-voltage components.
User-level checks:
- Open the cavity and locate the waveguide cover (usually a small rectangular mica or plastic plate on the side wall).
- Inspect for burn marks, bubbling, or holes. If damaged, stop using the microwave.
- Clean the cavity walls and around the waveguide cover with mild detergent and a soft cloth. Remove all food splatters and grease. Do not soak the waveguide cover.
Part replacement:
- If the waveguide cover is burned or cracked, replace it with a genuine Balay waveguide cover cut to the correct size for your model.
- If loud humming persists or E04 returns after replacing the cover and cleaning, a technician must test the high-voltage diode and magnetron for shorts.
Do not operate the microwave with the waveguide cover removed or damaged, as this can damage the magnetron and create a fire risk.
Repair Difficulty
Required Part
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