E4
Mitsubishi Electric
Indoor Unit EEPROM or Configuration Error
Indoor unit shows E4, unit may not respond to remote commands
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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
Incorrect indoor PCB for model, Corrupted configuration data, Failed EEPROM IC, Power surge damage
How to Fix / Troubleshooting
Safety first: Disconnect power at the breaker before opening the control box.
Steps:
- Confirm model compatibility: If the indoor PCB was recently replaced, verify that the part number matches the exact Mitsubishi Electric model and capacity. Incorrect boards can trigger E4.
- Factory reset: Perform a full power reset (breaker OFF for 10 minutes). Some models allow a service reset via the remote or DIP switch settings on the PCB—refer to the service manual.
- Check DIP switches/jumpers: Ensure any configuration switches on the PCB (capacity, system type, address) are set according to the installation manual.
- Inspect PCB: Look for obvious damage or missing components near the memory IC. If damaged, the board must be replaced.
- Replace PCB: If configuration and wiring are correct and E4 persists, replace the indoor control PCB with the correct Mitsubishi Electric part.
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Repair Difficulty
Hard
4/5
Required Part
Indoor Control PCB
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