Microwave displays E4 and stops heating; the fan and light may still operate.
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 even when unplugged. Do not attempt high-voltage (HV) repairs unless you are trained and equipped to safely discharge capacitors and follow microwave service procedures.
User-level actions:
- Unplug the microwave for 10 minutes, then plug it back in and test with a cup of water. If E4 returns and the water remains cold, discontinue use.
- Ensure the unit is not running empty; always test with a a microwave-safe load (e.g., 1 cup of water).
Any further diagnosis (testing the magnetron, transformer, capacitor, or diode) should be performed by a qualified technician with proper tools. Due to the inherent risks, most homeowners should replace the unit or have it professionally serviced rather than attempting a DIY repair.