Display shows E04 and water flow through the softener is severely reduced or stopped.

Safety first: Turn off the inlet and outlet valves to the softener and relieve pressure.

• Check bypass position: Confirm the AquaSoft bypass valve is in the correct "Service" position, not in bypass or closed.
• Inspect inlet screen: Remove the inlet fitting (follow AquaSoft manual) and check for sediment or iron buildup on the inlet screen. Clean with a soft brush and rinse.
• Clean flow sensor: Locate the flow sensor/turbine assembly on the outlet side of the control head. Remove it carefully, noting orientation. Rinse the turbine under running water and remove any debris. Ensure the turbine spins freely.
• Check wiring to sensor: Inspect the small sensor harness from the flow sensor to the control board. Reseat connectors and look for damage.
• Reassemble and test: Reinstall the flow sensor and inlet fittings, open valves slowly to purge air, then restore power. Run water at a faucet and confirm that the display shows flow and that E04 clears.