E12 error and the unit displays a sensor temperature out-of-range message (on models with temperature monitoring).

Safety first: Unplug the softener before handling sensors. Hot water can cause burns; ensure you are working on the cold-water line.

• Confirm plumbing: Verify the Clearwater softener is installed on the cold-water supply only. Hot water entering the unit can damage the sensor and resin.
• Check probe seating: Ensure the temperature sensor is fully inserted into its well or port on the control valve or plumbing manifold.
• Inspect wiring: Look for cuts, pinches, or loose connectors on the sensor harness.
• Reset and test: Power-cycle the unit to clear E12. If the error returns immediately and water is cold, the sensor is likely defective.

Replace the Clearwater temperature sensor probe if it continues to report out-of-range values.