Microwave runs but does not heat; display may show E03 after a few seconds.

Danger: High-voltage components inside a microwave can cause severe injury or death. Only qualified technicians should work on the HV circuit. Users should limit themselves to external checks.

User-level checks:

• 1. Confirm correct power supply: Plug the microwave directly into a properly grounded wall outlet. Avoid extension cords or multi-plugs that may drop voltage.
• 2. Test with a known-good outlet: Try another outlet on a different circuit to rule out supply issues.
• 3. Perform a water heating test: Place a large mug of water inside and run for 2–3 minutes. If the turntable rotates and the light is on but the water remains cold and E03 appears, the HV system is likely at fault.

Technician-level checks:

• Check continuity of the magnetron and its thermal cut-out (thermal fuse) using a multimeter.
• Test the primary and secondary windings of the high-voltage transformer.
• Inspect wiring and connectors between the control board and HV components for burns or loose connections.

Resolution: Replace the failed HV component (transformer, diode, capacitor, or thermal fuse) with the correct IKEA-compatible part. In many cases, replacing the transformer and diode together is recommended.