E04 error and the display shows incorrect time or settings after power interruptions.

Safety first: Disconnect power before removing the control panel cover. Do not touch exposed circuitry with wet hands.

Step-by-step:

• 1. Power cycle: Unplug the softener for 5 minutes, then plug it back in. Check if E04 clears and if the clock can be reset and retained.
• 2. Inspect power supply: Verify the AquaHouse power adapter is the correct voltage and firmly plugged into both the outlet and the control head. Test the outlet with another device.
• 3. Check board connections: Remove the control cover. Inspect the low-voltage connector from the adapter to the PCB and any ribbon cables to the display. Reseat all connectors.
• 4. Reset to factory defaults: Use the installer menu (refer to AquaHouse manual) to perform a factory reset. Re-enter hardness, capacity, and time-of-day settings.
• 5. Observe after outage: Simulate a brief power loss by unplugging for 30 seconds. If E04 returns or settings are lost, the PCB's memory circuit is failing.

Persistent E04 or loss of programming after short outages usually requires replacing the AquaHouse main control board.