Microwave display shows E4 and unit will not start; sometimes appears after a power surge or lightning storm.

Safety first: Unplug the microwave before removing any panels.

Step-by-step checks:

• 1. Power reset: Unplug the microwave for at least 5 minutes to allow the control to fully discharge. Plug back in and check if E4 clears. Sometimes a temporary logic fault is reset this way.
• 2. Check outlet and surge protection: Verify the outlet voltage is stable and within specification (typically 120V or 230V depending on region). Use a surge protector to prevent future damage.
• 3. Inspect control panel connections (experienced DIYers): Remove the outer cabinet and control panel screws. Carefully tilt the control panel forward. Locate the flat ribbon cable from the keypad to the control board and any other harness connectors.
• 4. Reseat connectors: Gently unplug and reinsert the ribbon cable and harness connectors to ensure good contact. Do not bend or crease the ribbon.
• 5. Visual inspection: Look for burnt components, darkened areas, or bulging capacitors on the control PCB. Any visible damage usually means the board must be replaced.
• 6. Replace control board if needed: If E4 persists after reseating connectors and power reset, the main control board or its EEPROM is likely faulty. Replace with the exact Midea control PCB part number for your model.

If you are uncomfortable working around electronic boards or cannot identify the correct replacement, contact a professional technician.