Display shows SN1 or SENS1, spa may not heat or may shut down, temperature reading may be erratic.

Safety first: Turn off power at the GFCI breaker before accessing the control pack or heater area.

• Locate the temperature sensor: On most Artisan Spas, the primary temp sensor is threaded or clamped into the heater tube or plumbing near the heater.
• Inspect wiring and connector: Follow the sensor cable to the control board. Check for cuts, chew marks, or pinched sections. Ensure the plug is fully seated and free of corrosion.
• Check resistance (if you have a multimeter): Disconnect the sensor from the board and measure resistance across the two leads. Compare to a thermistor chart (e.g., around 10k ohms at 77°F/25°C). A reading of 0 ohms (short) or infinite (open) indicates a bad sensor.
• Replace sensor if faulty: Unscrew or unclamp the sensor from the heater tube. Some water may leak; be prepared with towels. Install a new Artisan-compatible temperature sensor with fresh O-ring or gasket, tightening snugly but not overtightening.

After replacement, restore power and verify that the displayed temperature is reasonable and that the SN1 error is cleared.