Sn2
Catalina Spas
High-Limit or Secondary Sensor Failure
Display shows Sn2 or SENS2; 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
Failed high-limit sensor on heater tube, Loose sensor connection at Catalina control board, Damaged sensor harness, Moisture ingress in sensor head
How to Fix / Troubleshooting
Safety: Disconnect power at the GFCI before servicing sensors.
- Step 1 – Reset: Turn off power for several minutes, then restore. If Sn2 reappears quickly, proceed with inspection.
- Step 2 – Locate secondary sensor: On many Catalina spa packs, the secondary or high-limit sensor is mounted alongside the main temperature sensor on the heater tube. Identify the second sensor and trace its cable to the board.
- Step 3 – Check connections: Unplug and replug the sensor connector several times to wipe oxidation from the contacts. Inspect for green corrosion or water damage on the plug and board header.
- Step 4 – Replace sensor: If wiring looks good and Sn2 persists, replace the secondary/high-limit sensor with a Catalina-approved part. Use a new o-ring and ensure a watertight seal.
- Step 5 – Monitor operation: Restore power and run the spa through a full heat cycle, confirming that Sn2 does not return and the spa heats normally.
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Repair Difficulty
Medium
3/5
Required Part
High-Limit Sensor
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