Display shows E12 and the Aquabion softener reports an internal leak or unexpected water movement.

Safety first: Turn off power and close inlet and outlet valves. Place towels or a tray under the unit.

• Check for visible leaks: Inspect around the control head, inlet/outlet unions, and bypass valve for drips or mineral tracks. Tighten unions gently if needed.
• Inspect drain outlet: With the unit in service and no water being used, check the drain line. Any continuous flow indicates an internal valve leak.
• Test bypass: Move the Aquabion bypass to bypass mode. If flow to the house continues or leaks persist, the bypass may be faulty and require replacement.
• Internal valve service: If leaks are internal (water to drain when idle), the rotor and seal kit or check valves inside the control head may need replacement. This involves depressurizing, removing the control head, and rebuilding it with new seals per Aquabion instructions.
• Flow sensor check: If no actual leak is found but E12 persists, inspect and test the turbine flow sensor for sticking or electrical faults.

Warning: Internal valve repairs can be complex. If you are not experienced with water softener valves, consider professional service to avoid creating larger leaks.