SN1
AquaRest Spas
Primary Temperature Sensor Failure
Display shows SN1 or SENS1 and spa will not heat; temperature reading may be very low or dashed.
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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 primary temperature sensor, Damaged sensor cable or connector, Sensor not fully seated in heater well, Corroded sensor plug on control board
How to Fix / Troubleshooting
Safety: Turn off power at the GFCI breaker before accessing the control pack or heater.
- Step 1 – Locate the sensor: Open the equipment compartment and find the primary temperature sensor inserted into the heater tube or a dry well on the AquaRest control pack.
- Step 2 – Inspect cable and plug: Follow the sensor cable to the control board. Check for cuts, rodent damage, or pinched sections. Unplug the sensor connector, inspect for corrosion or moisture, dry if needed, and firmly reconnect.
- Step 3 – Reset power: Restore power and see if SN1 clears. If the error persists, the sensor is likely defective.
- Step 4 – Replace sensor: Remove the old sensor from the heater tube or well. Install a new AquaRest-compatible temperature sensor, ensuring it is fully seated and any O-rings or gaskets are properly positioned to prevent leaks.
If SN1 remains after sensor replacement, the control board's sensor circuit may be faulty and should be evaluated by a technician.
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Repair Difficulty
Medium
3/5
Required Part
Primary Temperature Sensor
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