Pool Error Codes

Raypak SNS: Temperature Sensor Malfunction

SNS means one of the heater's temperature sensors is reporting a value the control board considers impossible.

The temperature reading on the panel isn't tracking reality anymore — it's stuck, jumping around, or just replaced by SNS outright. Unlike a flow or ignition fault, this one isn't about the heater failing to do something; it's the control board flagging a sensor input that's fallen outside a range it can trust, roughly 36-110°F, and refusing to act on bad data rather than heat or shut down based on a number that might be wrong. That caution is deliberate: a heater that kept running on a bad temperature reading could easily overheat the water or never satisfy the thermostat at all, so the safer move is to stop and report the sensor fault instead of guessing.

Medium severity

Applies to: Raypak Digital ASME and low-profile residential gas pool/spa heaters

What it means

Temperature sensor malfunction — a temperature sensor is reading outside its valid range (roughly 36-110°F) or its circuit appears open/shorted. Because the heater relies on that reading to decide when to fire and when to stop, an unreliable sensor gets flagged immediately rather than left to quietly cause overheating or undershooting the set temperature.

Likely causes

What you can check yourself

  1. Power-cycle the heater to see if the reading recovers
  2. With power off, check that the sensor connector at the board is fully seated
Call a professional if…

A persistent SNS code typically means the sensor needs replacement — a quick job for a pool heater technician.

Sources

Related

This site is an independent reference, not a substitute for a licensed pool professional. Gas pool heaters can leak carbon monoxide and cause fire; pump and heater electrical circuits carry mains voltage. Anything involving the gas line, burner assembly, or house wiring should be handled by a licensed technician or electrician.