E05 displayed and the unit does not regenerate at the programmed time.

Safety: No internal high-voltage work is required for basic checks, but unplug the unit if removing the control panel.

Steps:

• Verify time and date: Enter the AquaClean programming menu and confirm the current time, date, and regeneration schedule are correct. Adjust if needed.
• Check power stability: If the softener frequently loses time after outages, consider using a surge protector or UPS to stabilize power.
• Inspect control board: Remove the control cover and look for a backup battery or capacitor (if present). If visibly leaking or swollen, the board may need replacement.
• Factory reset: Perform a control reset according to the AquaClean manual, then reprogram hardness, time, and regeneration settings.

If E05 returns after correct programming and stable power, the internal clock circuit on the AquaClean main control board is likely defective and the board should be replaced.