E15
Monarch Internal Communication / Bus Error

E15 displayed and the unit reports an internal communication error between display and main board

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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 ribbon cable between display and main PCB, Oxidised connector pins, Faulty display module, PCB communication driver failure

How to Fix / Troubleshooting

Safety first: Disconnect power before opening the control housing.

  • Reseat ribbon cable: Carefully unplug and replug the flat ribbon cable or harness between the display/keypad and the main board. Ensure it is fully inserted and latched.
  • Inspect connectors: Look for bent pins, corrosion, or contamination on the connectors. Clean gently with contact cleaner if necessary.
  • Check for physical damage: Examine the display PCB for cracks or broken components, especially if the unit has been knocked.
  • Test after reassembly: Restore power and see if the display operates normally. If E15 persists, either the display module or main PCB may need replacement.
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Repair Difficulty

Medium 3/5

Required Part

Display / Keypad Module
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