Microwave displays E3 and will not start; sometimes appears after a power surge or lightning storm.

Safety first: Unplug the microwave before opening any panels.

Step-by-step:

• Power reset: Unplug the Clatronic microwave for 5–10 minutes to allow the control board to fully discharge. Plug back in and check if E3 clears.
• Check for stuck keys: Press each button on the keypad firmly and individually. If any key feels stuck or does not click, gently clean around it with a slightly damp cloth (power off) and dry thoroughly.
• Inspect for moisture: If the microwave is above a stove, steam can enter the control panel. Let the unit dry for several hours (unplugged). Avoid using it while heavy steam is rising from the cooktop.
• Check keypad ribbon cable: Remove the control panel cover (unplugged). Locate the flat ribbon cable from the membrane keypad to the control PCB. Reseat it carefully, ensuring it is fully inserted and not corroded.
• Replace keypad or control board: If E3 persists, the membrane keypad or control PCB is likely faulty. These are usually replaced as assemblies.

Warning: Do not touch the high-voltage section when the cabinet is open. If unsure, contact a professional.