Microwave runs (light and fan on) but does not heat; display shows E03 after a few seconds.
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 lethal voltages even when unplugged. Do not attempt high-voltage repairs unless you are properly trained and equipped.
User-level checks:
- Confirm you are using microwave-safe cookware and not running the oven empty; running empty can damage the magnetron.
- Try heating a cup of water for 1–2 minutes to verify no heating.
- Check that the power level is set above 0 and that the timer is not in a special mode (e.g., defrost with very low power).
Technician-level checks (summary only):
- Unplug the unit and discharge the high-voltage capacitor using proper insulated tools and procedures.
- Test the high-voltage diode and capacitor with a suitable meter; replace if shorted or open.
- Check the primary and secondary windings of the high-voltage transformer for continuity.
- Test the magnetron filament for continuity and inspect for burn marks or cracks.
Recommendation: Due to the risk involved, E03 faults should normally be handled by an authorized Teka service technician.