Safety first: Before opening the unit, disconnect power at the breaker. High voltage can still be present inside.

Step 1 – Check household power: Verify the outlet has power by plugging in another device. Check the circuit breaker or fuse panel for a tripped breaker.
Step 2 – Inspect power cord: Ensure the Thermador microwave power cord is fully inserted and not damaged.
Step 3 – Internal fuse check (qualified persons): Remove the outer cover and locate the internal line fuse near the power entry. Test it with a multimeter. If blown, investigate for underlying causes (shorted components) before replacing.
Step 4 – Check line filter and wiring: Inspect the line filter board and wiring for burn marks or loose connections.
Step 5 – Control board: If the fuse and line filter are good but the unit remains dead, the main control board may be defective and require replacement.

Warning: Never bypass the internal fuse; always replace with the correct rating.

Microwave will not power on at all; display is blank and no lights or sounds occur.

Possible Causes