Control panel displays Sn2 and spa may not heat or may shut down.

Safety: Shut off power at the GFCI breaker before working on the spa.

• Locate sensor 2: Remove the equipment panel and find the heater tube attached to the Canadian Spa Company spa pack. The hi-limit/secondary sensor is usually mounted in or on the heater tube and plugs into a separate port (often labeled HI-LIMIT or SENSOR 2).
• Inspect mounting: Ensure the sensor is fully inserted into its well or clamped firmly to the heater tube. A loose sensor can misread temperature and trigger Sn2.
• Check wiring and plug: Follow the cable from the sensor to the spa pack. Look for abrasions, rodent damage, or melted insulation. Unplug the connector, inspect for corrosion or moisture, dry if needed, and reconnect securely.
• Resistance test: With power OFF, measure resistance across the sensor leads and compare to the expected thermistor chart. Replace if open, shorted, or far out of range.
• Replace sensor if needed: Remove the old hi-limit sensor, install a new Canadian Spa Company-compatible hi-limit sensor with proper sealing (O-ring or gasket), and reconnect to the same port.
• Restore power: Turn the GFCI back on and verify that Sn2 clears and the spa heats normally.

If Sn2 persists with a known-good sensor, the spa pack’s sensor input may be faulty and the control pack may need replacement by a professional.