E18 error and the unit reports abnormal conductivity or hardness after regeneration (on models with sensor)

Safety first: Turn off power before disconnecting any sensor wiring. Close valves if removing in‑line sensors.

• Locate sensor: Some Nobel softeners include an in‑line water quality sensor on the outlet line or in a sampling cell. Identify the probe and its cable.
• Clean probe: Remove the sensor according to the manual. Soak the probe tip in a mild descaling solution (e.g., diluted vinegar) to remove scale and iron deposits. Rinse thoroughly with clean water.
• Check installation: Ensure the sensor is installed in the correct flow direction and is fully wetted during operation. Avoid installing in areas with air pockets.
• Inspect wiring: Verify the sensor cable is intact and firmly connected to the control board. Repair or replace damaged cables.
• Reset alarm: Reinstall the sensor, restore power, and clear E18 via the control panel. Run water and observe the sensor reading for stability.

If E18 returns with a clean, correctly installed sensor, the sensor or control board input may be defective and require replacement.