Microwave displays E18 and immediately cancels any attempt to start a cycle.

Safety first: No internal high-voltage work is required for this check; keep unit plugged in for keypad tests.

• Step 1 – Disable child lock: On most Thermador models, press and hold the designated key (often "Stop/Cancel" or a lock icon) for 3–5 seconds to toggle the child lock. Consult your user manual for the exact combination.
• Step 2 – Power reset: If the lock will not clear, disconnect power for 5 minutes, then restore and try again.
• Step 3 – Test keypad: Press all keys to ensure none are stuck or unresponsive. A stuck key can cause the control to think the lock is engaged.
• Step 4 – Inspect keypad ribbon (qualified persons): Remove the control panel and reseat the keypad ribbon cable on the control board.
• Step 5 – Replace keypad or control: If E18 persists, replace the membrane keypad or user interface panel. If still unresolved, replace the main control board.

Note: Avoid pressing the keypad with excessive force to prevent membrane damage.