Safety first: Turn off power at the GFCI breaker before working inside the equipment bay.

Steps:

Power reset: Turn breaker OFF for a few minutes, then ON. If Sn3 clears and does not return, continue to monitor.
Locate the auxiliary sensor: Some Dream Maker Spas use a third sensor for ambient or cabinet temperature. It may be clipped to plumbing or mounted inside the equipment bay. Follow the cable from the SENSOR 3 or AUX port on the control pack.
Inspect and reseat connector: Unplug the sensor from the board, inspect for corrosion or moisture, and plug it back in firmly.
Check cable condition: Look for pinched, cut, or chewed insulation. Replace the sensor if the cable is damaged.
Replace sensor if faulty: If you have resistance readings that are open or far off spec, install a compatible auxiliary sensor for your specific control pack.
Board issues: If a known-good sensor still gives Sn3, the control board may be defective and should be evaluated or replaced by a spa technician.

Control panel displays Sn3 and spa may not heat or may shut down

Possible Causes