Microwave displays E18 and may not accept new settings; sometimes appears after keypad lock/child lock use.

Safety first: No internal high-voltage work is required for this check, but unplug before removing any panels.

• Disable child lock: Follow the user manual to turn off the child lock (often by holding a specific key for several seconds). Confirm that the lock icon disappears.
• Power cycle: If the lock cannot be disabled, unplug the microwave for 10 minutes, then reconnect and try again.
• Check lock button: Ensure the lock-related button is not physically stuck or damaged. Clean around the button with a slightly damp cloth.
• Keypad or board replacement: If E18 persists and the lock cannot be controlled, the keypad or control board may be defective and should be replaced.

Warning: Do not attempt to bypass safety lock functions by altering wiring.