SN2
AquaRest Spas
Secondary / High-Limit Sensor Failure
Display shows SN2 or SENS2; spa may run but heater is disabled or behaves 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 temperature sensor, Loose sensor on heater tube, Damaged sensor harness, Faulty sensor input on control board
How to Fix / Troubleshooting
Safety: Shut off power at the breaker before working on sensors or wiring.
- Step 1 – Identify secondary sensor: In the equipment bay, locate the second sensor on the heater tube or control pack (often labeled HI-LIMIT or SENSOR B).
- Step 2 – Check mounting: Ensure the sensor is firmly clamped or threaded into the heater tube and making good thermal contact. A loose sensor can misread temperature.
- Step 3 – Inspect wiring: Follow the sensor cable to the control board. Check for damage and confirm the connector is fully seated in the correct port.
- Step 4 – Power cycle: Restore power and monitor the display. If SN2 returns, replace the secondary sensor with a compatible AquaRest part.
If replacing the sensor does not clear SN2, the control board may require repair or replacement.
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Repair Difficulty
Medium
3/5
Required Part
Secondary / High-Limit Sensor
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