Control panel displays Sn1 and spa will not heat or shows incorrect water temperature

Safety first: Turn off power at the spa’s GFCI breaker and verify with a non-contact voltage tester before opening any panels. Water and electricity are dangerous together.

Step-by-step checks:

• Power cycle the spa: Turn the GFCI breaker OFF for 2–3 minutes, then ON. If Sn1 clears and does not return, it may have been a temporary logic fault.
• Inspect the sensor connection: Remove the equipment access panel. Locate the control pack (Balboa/Gecko style pack used in many Dream Maker Spas). Find the plug labeled TEMP or SENSOR 1. Unplug and re-seat the connector several times to clean the contacts. Look for corrosion, moisture, or burnt pins.
• Check the sensor cable: Follow the cable from the control pack to the heater tube or sensor well. Look for cuts, crushed insulation, or rodent damage. If damaged, the sensor must be replaced.
• Test the thermistor (if you have a meter): With power OFF, disconnect the sensor from the board. Measure resistance across the two sensor leads. At about 77°F (25°C), most spa thermistors read roughly 10kΩ (check Dream Maker/pack documentation). If the reading is open (infinite) or very different from expected, the sensor is bad.
• Replace the temperature sensor: If faulty, order a compatible Dream Maker/Balboa/Gecko temperature sensor for your specific control pack. Remove the old sensor from the heater tube or sensor well, install the new one with the supplied o-ring, and tighten only hand-snug to avoid cracking the well. Route the cable away from hot or moving parts.
• If Sn1 persists: After replacing the sensor, if the error remains, the sensor input circuit on the control board may be defective. At this point, replacement of the control pack or main PCB is recommended by a qualified spa technician.