E4
Swan Control PCB Communication / EEPROM Error

Microwave displays E4 and will not start, sometimes after a power surge or outage.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Corrupted control board memory (EEPROM), Loose ribbon cable between display PCB and main PCB, Power surge damage to control PCB, Faulty touch control panel

How to Fix / Troubleshooting

Safety: Disconnect the microwave from mains before opening any panels.

  • Step 1 – Power reset: Unplug the microwave for 10–15 minutes to allow the control board to fully discharge. Plug back in and check if E4 clears.
  • Step 2 – Inspect control connections: Remove the control panel assembly (usually held by screws behind the trim). Check the ribbon cable between the keypad/display board and the main control PCB. Reseat the cable carefully, ensuring it is fully inserted and not damaged.
  • Step 3 – Check for moisture: Look for signs of moisture or steam damage around the control panel area. Dry gently with a soft cloth and allow the unit to air dry for several hours before retesting.
  • Step 4 – Visual inspection of PCB: Examine the main control PCB for burnt components, cracked solder joints, or corrosion. If visible damage is present, the board should be replaced.

If E4 persists after reseating cables and power resetting, the control PCB or EEPROM is likely faulty and requires replacement, typically a job for a professional technician.

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Repair Difficulty

Hard 4/5

Required Part

Main Control PCB
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