E03
Telefunken High Voltage System Failure (Magnetron / Inverter / HV Transformer)

Microwave runs (light and fan on) but does not heat food; after a short time, E03 appears on the display.

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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

Failed magnetron, Failed high-voltage transformer or inverter module, Open high-voltage diode, Blown high-voltage capacitor

How to Fix / Troubleshooting

Critical safety warning: The high-voltage section of a microwave (transformer/inverter, capacitor, diode, magnetron) can be lethal. Do not attempt HV testing unless you are trained and have proper tools. Always unplug the unit and discharge the capacitor properly.

  • Basic user checks: Confirm that the correct power level and time are set. Try heating a cup of water for 1–2 minutes. If there is no warmth and E03 appears, the issue is internal.
  • Visual inspection (for trained persons): Remove the outer cover. Look for obvious signs of damage: burnt connectors on the high-voltage transformer or inverter board, bulged or leaking HV capacitor, or charred HV diode.
  • Component replacement: If a specific component is visibly damaged (e.g., cracked HV diode, bulged capacitor), replace it with a Telefunken-compatible part of identical rating. Magnetron replacement should be done only by professionals due to RF sealing and safety checks.
  • If unsure: Reassemble the unit and contact an authorized Telefunken service center. Do not operate the microwave with suspected HV faults.
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Repair Difficulty

Professional Required 5/5

Required Part

Magnetron
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