Microwave shows E05 and stops mid-cycle or will not start; sometimes accompanied by a beeping alarm.

Safety warning: Inverter-based microwaves operate at very high voltage and frequency. Only qualified technicians should service the inverter or magnetron.

• Step 1 – Power cycle: Disconnect power for 10 minutes to allow the inverter and control to reset. Restore power and test.
• Step 2 – Ventilation check: Ensure vents are clear and that the unit is not installed too tightly in cabinetry, which can cause inverter overheating.
• Step 3 – Inspect wiring (qualified persons): With power disconnected, remove the outer cover and inspect harness connections between the main control board, inverter board, and magnetron. Reseat any loose connectors.
• Step 4 – Component diagnosis: If E05 returns, the inverter board or magnetron is likely defective. Specialized tests and replacement should be performed by a Thermador-authorized technician.

Recommendation: Due to shock risk and complexity, do not attempt inverter board replacement without proper training.