E18 displayed and unit indicates resin tank temperature out of range

Safety first: Disconnect power before removing covers or handling sensors. Do not operate the softener if it has been exposed to freezing temperatures until it has fully thawed and been inspected for cracks.

Step-by-step:

• Inspect probe placement: Ensure the AquaUnique resin tank temperature probe is properly attached to the tank surface or well, as designed.
• Check for physical damage: Look for cuts, abrasions, or crushed sections of the sensor cable.
• Reseat connector: At the control board, unplug and replug the sensor connector to ensure a good contact.
• Allow stabilization: If the unit was recently exposed to extreme temperatures, allow it to reach room temperature and then clear the error.

When to call a technician: If E18 remains, the sensor or control board must be tested and replaced as needed.