E12
SMEG Low Line Voltage or Power Supply Error

Microwave displays E12; clock and basic functions may work but cooking cannot be started.

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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

Undervoltage from mains supply, Faulty internal power supply board, Loose mains connection, Damaged mains filter (EMI) board

How to Fix / Troubleshooting

Safety: Unplug the microwave before inspecting the power cord or plug. Do not open the cabinet unless qualified.

Supply checks:

  • Plug the microwave directly into a wall outlet (no extension leads or multi-way adaptors).
  • Test the outlet with another high-power appliance to confirm it delivers stable power.
  • If possible, try a different outlet on a separate circuit.

Reset:

  • Unplug the microwave for 10 minutes, then plug back in and set the clock. Attempt a short heating cycle.

Technician checks:

  • Inspect the mains filter/EMI board and wiring for heat damage or loose connections.
  • Measure the low-voltage outputs from the power supply to the control PCB.
  • Replace the power supply or control PCB if voltage regulation is faulty.

If E12 persists with a known good power supply, internal electronics will require professional service.

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Repair Difficulty

Hard 4/5

Required Part

Power Supply Board
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