Control panel shows E01 and the softener will not start a regeneration cycle.

Safety first: Unplug the AquaClean water softener or switch off the dedicated breaker before removing any covers.

Steps to check:

• Power reset: Disconnect power for 5 minutes, then restore power and see if E01 clears. Sometimes a brief surge can lock the board.
• Inspect wiring harness: Remove the control panel cover. Check the main wiring harness plug on the AquaClean control board. Ensure it is fully seated and that no pins are bent or corroded.
• Check low-voltage connector: Verify the small low-voltage connector from the power supply to the control board is tight and free of corrosion.
• Look for board damage: Inspect the control board for burn marks, swollen components, or moisture. If present, the board is likely defective.
• Test outlet: Confirm the wall outlet supplies correct voltage with a multimeter. Low or unstable voltage can trigger E01.

If E01 persists after reseating connectors and power reset, the main control board will typically need replacement. Label and photograph all connections before removing the old board to ensure correct reinstallation.