SN2
Arctic Spas
Secondary or High-Limit Sensor Failure
Display shows SN2 or SENSOR2, spa may run but heater may be disabled or behave erratically.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Open or shorted secondary sensor (Arctic Spas hi-limit thermistor), Damaged sensor harness, Corroded connector at control board, Control board sensor channel failure
How to Fix / Troubleshooting
Safety first: Shut off power at the GFCI breaker.
- Identify the second sensor: The SN2 sensor is typically the high-limit or secondary temperature sensor mounted on or near the heater tube.
- Inspect wiring: Follow the sensor cable from the heater to the control pack. Check for damage, pinching, or melted insulation.
- Check connector: Unplug the sensor from the board and inspect for moisture or corrosion. Dry and clean with contact cleaner if needed.
- Measure resistance: Use a multimeter to measure resistance across the sensor leads. Compare to Arctic Spas thermistor charts. Replace the sensor if readings are not within expected range.
- Replace sensor: Install a new Arctic Spas high-limit/secondary sensor, ensuring it is properly seated in its well or clamped to the heater tube.
- Board issues: If a known-good sensor still triggers SN2, the control board may be defective and should be evaluated by a spa technician.
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Repair Difficulty
Medium
3/5
Required Part
Arctic Spas high-limit sensor
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