E23
CTC Configuration / EEPROM Fault

Boiler displays E23; internal memory or configuration error.

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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

Corrupted configuration data, Incompatible replacement PCB, Power surge affecting memory

How to Fix / Troubleshooting

Safety: Isolate power before accessing electronics.

  • Power reset: Turn off the boiler at the isolator for at least 30 seconds, then restore power and check if E23 clears.
  • Reload parameters (technician): Using the CTC service tool or installer menu, reload factory default parameters and re-enter system-specific settings.
  • Check PCB version: Ensure any replacement PCB is the correct model and firmware version for the specific CTC boiler.
  • Replace PCB: If configuration cannot be restored or E23 persists, replace the main control PCB.
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Repair Difficulty

Hard 4/5

Required Part

Main Control PCB
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