Display shows E05 and the unit remains in bypass or emergency mode

Safety: Disconnect power and close inlet and outlet valves. Relieve pressure via a nearby tap.

• Check mechanical coupling: Remove the control cover and verify that the motor shaft is firmly coupled to the valve cam or piston. Replace any cracked couplings or cams.
• Inspect for obstructions: Disassemble the valve head according to Grünbeck documentation. Look for resin beads, scale flakes, or foreign objects blocking the valve channels.
• Clean and descale: Clean all internal parts with clean water. Use an approved descaling agent on scale-encrusted parts, then rinse thoroughly. Replace O-rings and seals if they appear flattened or damaged.
• Correct reassembly: Ensure all parts are reinstalled in the correct orientation. Misaligned parts can prevent the valve from reaching its programmed positions.
• Test cycle: Reassemble, open valves slowly, restore power, and run a full manual regeneration to verify that all positions are reached without error.