Display shows E02 and regeneration stops shortly after starting

Safety: Disconnect power. Be prepared for water discharge when opening hoses.

• Check drain hose routing: Ensure the drain hose from the Grünbeck valve head to the waste connection is not kinked, crushed, or routed uphill beyond the manufacturer's maximum height.
• Clean drain outlet: Remove the hose from the drain connection or siphon. Flush the hose with water to clear sludge or salt deposits. Clean the siphon/air gap fitting thoroughly.
• Verify free flow: Place the hose into a bucket and start a manual regeneration (reconnect power briefly). Confirm a strong, steady flow during brine draw and rinse. Stop and disconnect power again after test.
• Inspect internal drain valve: If flow is weak despite a clear hose, the internal drain valve in the valve head may be obstructed by resin or debris. This typically requires disassembly of the valve head; if you are not experienced, contact a Grünbeck service technician.