E5
Atlantic Communication Error Between Display Panel and Main Control Board

Atlantic digital water heater shows E5 and refuses to start heating.

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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

Loose communication harness, damaged low-voltage cable, oxidized connectors, failed user interface board, failed main control board

How to Fix / Troubleshooting

Safety: Disconnect power at the breaker before removing any covers.

  • Remove the front cover to access both the user interface (display) board and the main control board.
  • Locate the low-voltage communication cable (often a multi-pin ribbon or small harness) between the two boards.
  • Unplug and replug the connectors on both ends several times to clean contacts. Inspect for bent pins or corrosion.
  • Check the cable for cuts or pinch points where it passes through the casing; replace the harness if damaged.
  • Restore power and see if E5 clears. If not, test by substituting a known-good display board or main board if available.
  • If only one board is replaced, ensure it is the correct Atlantic spare part reference for your exact model.
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Repair Difficulty

Hard 4/5

Required Part

User Interface Board
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