E05
Tier1 Power / Memory Fault

Display shows E05 and the time-of-day clock resets or drifts; programmed settings may be lost.

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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

Failing control board memory, Intermittent low-voltage power supply, Corroded control board connectors, Internal backup capacitor failure

How to Fix / Troubleshooting

Safety first: Disconnect the power supply before handling the control head.

  • Verify power source: Confirm the outlet is not controlled by a wall switch or timer. Use a different outlet if necessary. Check the Tier1 transformer for correct output voltage with a multimeter.
  • Inspect connectors: Remove the control head cover and gently reseat all low-voltage connectors on the control board. Look for corrosion or moisture; dry the area thoroughly if needed.
  • Reprogram and monitor: Set the correct time, hardness, and regeneration settings. Mark the current time and check after 24–48 hours. If the clock drifts significantly or resets after brief power interruptions, the board’s memory/backup circuit is failing.
  • Surge protection: Install a small surge protector on the outlet to protect the new board from future spikes.
  • Replace the board: If issues persist, replace the electronic control board / timer assembly with a Tier1-compatible part.
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Repair Difficulty

Medium 3/5

Required Part

Tier1 electronic control board / timer assembly
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