Microwave runs but does not heat; after several seconds E3 appears on the display.
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
Critical safety warning: The high-voltage section of a microwave (transformer, capacitor, diode, magnetron) can store and generate lethal voltages. Do not attempt to test or replace these parts unless you are a qualified appliance technician with proper tools and training.
User-level checks:
- Confirm that the microwave light, turntable, and fan operate when you start a cycle.
- Place a cup of water inside and run for 1–2 minutes. If the water remains cold and E3 appears, the heating circuit is not functioning.
- Unplug the unit and leave it unplugged. Do not continue to run it, as this can damage additional components.
Technician actions (for reference only):
- Test the high-voltage diode and capacitor with appropriate equipment after safely discharging the capacitor.
- Check the magnetron for correct resistance and signs of arcing or burning.
- Verify output of the high-voltage transformer and inspect wiring and connectors.