Safety: Isolate power and water before removing any sensor from the valve body.

Check installation conditions: Ensure the softener is not connected to a hot water line. Tapworks softeners must be installed on cold water only.
Inspect sensor wiring: Locate the temperature sensor on the valve body and follow its cable to the control board. Look for cuts, abrasions, or loose connectors. Reseat the plug.
Check sensor seating: Confirm the probe is fully inserted into its well in the valve body and secured with the retaining clip.
Measure resistance: With power off, disconnect the sensor and measure its resistance with a multimeter. Compare to Tapworks specifications at room temperature. An open or shorted reading indicates a bad sensor.
Replace sensor if faulty: Install a new Tapworks temperature sensor, ensuring correct orientation and sealing.
If E8 persists with a known good sensor: The control PCB input may be defective and the board will need replacement.

E8 error and the unit reports abnormal water temperature or shuts down

Possible Causes