Display shows “Err 04” and the unit fails to refill the brine tank with water after regeneration.

Safety first: Disconnect power and use bypass valves before opening the valve body.

• Check household water pressure: Ensure the main water supply is on and that there is adequate pressure (typically 20–125 psi). Very low pressure can prevent proper brine refill.
• Inspect refill flow control: Locate the brine refill flow control (often a small orifice or button in the valve body or brine line). Remove and check for debris, iron, or scale. Clean with warm water and a soft brush. Do not drill or enlarge the orifice.
• Examine rotor and seals: Remove the valve cover and inspect the rotor and seal kit. Look for cuts, flattening, or deformation around the refill port area. A damaged seal can block or misdirect refill water. Replace the rotor and seal kit if worn.
• Run a manual regen and observe: After reassembly, restore power and water. Start a manual regeneration and watch the brine tank during the refill stage. Confirm that water flows into the brine well. If not, verify that the brine line is not kinked and that the brine valve in the tank is not stuck closed.
• Control board timing: If mechanical parts are clean and intact but the unit never enters a refill stage (no click or motor movement), the electronic control board may not be commanding refill. Reprogram the unit and, if the issue persists, replace the control board.