Sn1 error and spa may not heat; temperature reading may be missing or show dashes.

Safety first: Disconnect power at the breaker before accessing sensors.

• Inspect sensor wiring: Locate the primary temperature sensor on the heater tube. Follow its cable to the control board and check for cuts, abrasions, or pinch points.
• Reconnect plug: Unplug the sensor from the control board and reconnect it firmly to ensure good contact.
• Replace sensor: If the error persists, replace the Sn1 temperature sensor with an Aquavia-compatible NTC probe. Ensure it is fully inserted into the heater tube and secured.
• Power up and test: Restore power and verify that the temperature displays correctly and the Sn1 code clears.