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Sn2 on a Jacuzzi / Sundance hot tub: temperature sensor fault

The water temperature sensor is open or shorted, and the heater is turned off. Depending on the model and year, this shows as Sn2 or Sn3.

Also shown as: SN2, Sn3, SN3

Most likely causes

  1. 1Failed temperature sensormost likely
  2. 2Loose or corroded connectorcommon
  3. 3Damaged sensor cablecommon
  4. 4Circuit board faultless common

What to try, in order

  1. Reset power at the breaker for 30 seconds.
  2. Check the water temperature with a thermometer before using the tub.
  3. With power off, look for damaged wiring in the equipment bay.
  4. Contact your dealer or a technician for a sensor replacement.

Sn2 questions

Is Sn2 or Sn3 the temperature sensor?

It depends on the model and year. Check your owner's manual. Both refer to a sensor fault that disables the heater.

Could it be the board and not the sensor?

It can be, but the sensor fails far more often. A technician can measure the sensor to confirm before replacing anything.

Related codes

Jacuzzi / Sundance -- · Watchdog shutdownJacuzzi / Sundance COOL · Water 20°F below setJacuzzi / Sundance FL1 · No flow detectedJacuzzi / Sundance FL2 · Flow switch stuck closedJacuzzi / Sundance FLO · Flow switch problemJacuzzi / Sundance HOLD · Panel buttons locked outJacuzzi / Sundance ICE · Freeze protection activeJacuzzi / Sundance OH · Overheat protection

General guidance. Follow your manufacturer's instructions; anything inside the control box is work for a licensed professional. Updated October 5, 2026.