Microwave runs but does not heat; display shows E03 after a few seconds of operation.
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 be lethal. The capacitor can hold a charge even when unplugged. Do not attempt to service these components unless you are trained and have proper tools to safely discharge the capacitor.
User-level checks:
- 1. Confirm symptom: Place a microwave-safe cup of water inside and run on HIGH for 1–2 minutes. If the turntable rotates and the light is on but the water remains cold and E03 appears, heating has failed.
- 2. Check power level settings: Ensure the power level is set to 100% (HIGH) and not a low setting that might be mistaken for no heat.
- 3. Inspect for burning smells or noises: If you hear loud humming, buzzing, or smell burning, unplug immediately and do not use again until inspected by a technician.
Technician-level actions:
- 4. Test magnetron: Remove the cabinet and test the magnetron for continuity and shorts to ground. Replace if open or shorted.
- 5. Test HV capacitor and diode: Discharge the capacitor safely, then test the capacitor and diode with appropriate methods. Replace any failed components with Westinghouse-compatible high-voltage parts.
- 6. Inspect HV transformer: Check for burnt smell, discoloration, or open windings.
Due to the danger of high voltage, this repair is best left to a professional appliance technician.