E11 error and the display shows an abnormally high or low water temperature reading (on models with temperature monitoring).

Safety first: Disconnect power before accessing the sensor.

• Locate sensor: Find the AquaSoft temperature sensor, typically inserted into a well on the valve body or plumbing.
• Check insertion: Ensure the probe is fully seated in the well and secured with its clip or nut.
• Inspect wiring: Follow the sensor cable to the control board. Look for cuts, abrasions, or loose connectors. Reseat the plug.
• Compare to actual temperature: Run water and measure temperature with a thermometer. If the display reading is far off, the sensor is likely defective.
• Replace sensor: Install a new AquaSoft temperature sensor probe. If E11 persists, the control board input may be faulty and require replacement.