Microwave runs (light and fan on, turntable may rotate) but food does not heat; E03 appears after a short time.
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. The high-voltage capacitor can remain charged even when unplugged. Only qualified technicians should service these components. Do not attempt if you are not trained.
User-level checks:
- 1. Confirm symptom: Place a microwave-safe cup of water inside and run for 1–2 minutes. If the water remains cold and E03 appears, heating is not occurring.
- 2. Check for obvious damage: Unplug the unit and remove the outer cabinet. Visually inspect the magnetron for burn marks, cracks, or melted terminals. Check the high-voltage wiring for signs of arcing or burning.
- 3. Listen for abnormal noises: A loud humming or buzzing from the transformer area can indicate a shorted magnetron or capacitor.
Technician-level actions (for professionals only):
- Discharge the high-voltage capacitor safely using a resistor-rated discharge tool.
- Test the magnetron for continuity between terminals and check for shorts to chassis.
- Test the high-voltage diode and capacitor with appropriate methods.
- Replace the failed component(s) with Grundig-compatible parts and re-test.
For non-professionals, if basic checks confirm no heating and E03 persists, discontinue use and contact a qualified appliance technician to replace the magnetron or other high-voltage components.