E16 error is displayed, and the unit reports a temperature or environment fault (on models with a temperature sensor).

Safety first: Disconnect power before accessing internal components.

• Check installation location: Ensure the softener is not installed in a freezing or excessively hot area (e.g., an unheated outbuilding in winter).
• Locate sensor: Identify the temperature sensor on the valve or PCB (refer to the model-specific manual).
• Inspect wiring: Confirm the sensor plug is firmly connected and the cable is intact.
• Allow temperature to normalize: If the unit has been exposed to extreme temperatures, allow it to return to normal room temperature and then power cycle.
• Replace sensor: If the error persists, replace the Aqua Dial temperature sensor with the correct part.