E10 error and the unit cannot detect the resin tank position

Safety first: Isolate the softener by placing it in bypass and disconnect power. Relieve pressure before opening the valve.

• Inspect piston movement: Remove the control head cover. On many Nobel valves, the piston is driven by a motor and cam. With power disconnected, gently pull the piston assembly (if accessible) to check for free movement. If it is seized, internal seals or debris may be binding it.
• Clean valve internals: Carefully disassemble the top section of the control valve according to the service manual. Remove the piston, seals, and spacers. Rinse all parts and the valve body with clean water, removing resin beads or scale.
• Check position sensor: Locate the position sensor (often a Hall sensor or micro‑switch near the cam). Ensure it is firmly mounted and the wiring is intact. If the sensor is physically damaged, it must be replaced.
• Reassemble and test: Reinstall the piston and seals in the correct order and orientation. Restore power and take the unit out of bypass. Initiate a manual regeneration and observe whether the valve now moves through all positions without triggering E10.

Because incorrect reassembly can cause leaks or cross‑connection of hard and soft water, this repair is best performed by an experienced technician if you are unsure.