Microwave does not heat and shows E3 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: High-voltage components inside a microwave (transformer, capacitor, diode, magnetron) can deliver lethal shocks even when unplugged. Do not attempt high-voltage repairs unless you are trained and equipped to safely discharge the capacitor. For most users, this repair should be left to a professional technician.
Basic checks you can safely perform:
- 1. Confirm symptom: Place a microwave-safe cup of water inside and run for 1–2 minutes. If the water remains cold and E3 appears, heating is not occurring.
- 2. Check power supply: Ensure the outlet is properly grounded and delivering correct voltage. Avoid using long or undersized extension cords.
- 3. Inspect for burning smell or noise: If you notice a strong burning smell, loud humming, or arcing sounds, unplug immediately and do not use the microwave.
- 4. Visual inspection (no contact): With the cabinet removed by a qualified person, visually inspect the magnetron terminals, high-voltage diode, and wiring for obvious burn marks or disconnected wires. Do not touch the capacitor or high-voltage wiring.
- 5. Professional service: Diagnosis of the magnetron, high-voltage diode, and transformer requires specialized tools and procedures. Contact an authorized Tristar service center to test and replace the defective component.