Sn2
Coast Spas
High-Limit Sensor Failure
Display shows Sn2, SN2, or SENSOR 2 error; spa may shut down heater and pumps intermittently.
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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 high-limit sensor, Loose or corroded sensor connector, Damaged sensor cable, Failed high-limit input circuit on control board
How to Fix / Troubleshooting
Safety first: Shut off power at the GFCI breaker before working on the heater or control pack.
- Identify high-limit sensor: Typically mounted on or in the heater tube separate from the main temperature sensor.
- Check connection: Reseat the high-limit sensor connector on the control board. Look for corrosion or moisture on the pins.
- Visual inspection: Inspect the sensor body for cracks, burn marks, or swelling. Replace if any damage is visible.
- Replace sensor: Remove the old high-limit sensor from the heater tube and install a new Coast Spas-compatible high-limit sensor with fresh sealing washer or O-ring.
- Do not bypass: Never bypass the high-limit sensor; it is a critical safety device.
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Repair Difficulty
Medium
3/5
Required Part
High Limit Temperature Sensor
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