The control panel displays 'Sn2', and the spa may not heat or may shut down.

Safety: Shut off power at the GFCI breaker before removing panels or touching wiring.

'Sn2' typically indicates a problem with the high-limit sensor that protects the heater from overheating.

• Reset power: Turn the breaker off for 2–3 minutes, then back on. If 'Sn2' reappears, proceed.
• Locate high-limit sensor: In the equipment bay, find the second sensor on or near the heater tube, often clipped or threaded into the manifold and labeled 'HI-LIMIT' or 'HL' on the control board.
• Check mounting: Ensure the sensor is firmly seated in its well or clamp and making good contact with the heater manifold.
• Inspect connector: Unplug the high-limit sensor from the board, inspect for corrosion or moisture, clean and dry if needed, then reconnect securely.
• Check cable: Look for kinks, cuts, or crushed sections along the sensor cable. Replace if damaged.
• Replace sensor if needed: With power OFF and water level managed as required, remove the old high-limit sensor, install the new Artesian-compatible high-limit thermistor with a new seal or clip, reconnect to the board, then restore power.

If 'Sn2' persists with a new sensor, the control board’s high-limit circuit may be defective and should be diagnosed by a spa professional.