E09 displayed and the unit fails to complete regeneration, often stopping at the rinse stage.

Safety: Turn off power and close the inlet valve. Be prepared for water discharge when disconnecting the drain line.

• Inspect drain hose: Follow the drain hose from the Hansgrohe valve head to the drain point. Straighten any kinks and ensure the hose is not crushed.
• Check drain height: Confirm that the drain line terminates at an appropriate height per Hansgrohe installation guidelines (usually below the valve head). Excessive height can prevent proper flow.
• Clean flow control: Remove the drain line from the valve. Locate and clean the drain flow control orifice, which may be inside the drain port. Rinse to remove iron, scale, or resin fines.
• Flush line: Run water through the drain hose with a garden hose to clear any blockages.
• Reassemble and test: Reconnect the drain line securely, restore water and power, and start a manual regeneration. Observe the drain discharge. If E09 recurs, the internal drain valve or piston may need service.