E3 error and the softener remains in service mode without regenerating on schedule

Safety first: Turn off power and close the inlet and outlet bypass valves before removing any plumbing connections.

• Locate the flow meter: On Nobel softeners, the flow meter (turbine sensor) is usually mounted on the outlet side of the control valve body with a small cable leading to the control board.
• Inspect wiring: Check that the flow sensor plug is firmly seated on the control board. Look for damaged insulation or pinched wires along the cable. Repair or replace damaged wiring.
• Clean the turbine: Shut off water and relieve pressure. Remove the flow meter housing from the control valve (usually held by clips or a threaded union). Carefully pull out the turbine wheel. Rinse under water and remove any sand, scale, or debris. Ensure the wheel spins freely on its shaft.
• Reassemble and test: Reinstall the turbine and housing, ensuring O‑rings are seated correctly. Open the bypass valves slowly and check for leaks. Restore power and run water at a nearby tap. The display should show flow or the usage counter should increment (if your model displays it).
• Clear error: Use the control panel to clear alarms or power‑cycle the unit. If E3 clears and the unit now tracks usage, monitor for a full day.

If E3 returns and no flow is being registered despite a clean turbine and good wiring, the flow meter assembly itself is likely faulty and should be replaced.