E11
Monarch Real-Time Clock / Memory Backup Fault

E11 displayed and the clock or regeneration time will not hold settings

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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 backup capacitor or battery on PCB, Faulty EEPROM memory, Frequent power interruptions without backup, PCB track damage around clock circuit

How to Fix / Troubleshooting

Safety first: Disconnect power before removing the control panel cover.

  • Check power stability: Ensure the softener is connected to a stable mains supply and not to a switched socket that is frequently turned off.
  • Reprogram settings: Follow the Monarch manual to reset the time, date, and regeneration parameters. Observe whether they are lost again after a short power interruption.
  • Inspect PCB: Look for a small backup battery or supercapacitor on the board. If visibly leaking or swollen, the PCB will need repair or replacement.
  • Use an uninterruptible supply: As a temporary workaround, connect the unit to a small UPS to maintain power during brief outages.
  • Replace PCB if needed: Persistent E11 errors usually indicate a failing control board that must be replaced.
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Repair Difficulty

Medium 3/5

Required Part

Control PCB
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