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SnR (Sensor Read)

Cal Spas Hot Tub

Severity: Moderate

Source: OnlyErrorCodes.com — Every error code. One place.

Cal Spas SnR Error Sensor Fault — Temperature Probe Fix

What Does This Error Mean?

Cal Spas SnR means the control board can't read the temperature sensor — sensor failed open, shorted, or wire damaged.
Sensor is mounted in the heater pipe with a small clip.
Replacement sensor is 25-60 USD; hour of work to swap.
Most Cal Spas sensors are NTC thermistors that read about 8-12k ohms at room temperature.

Affected Models

  • Cal Spas C-1000
  • Cal Spas C-2000
  • Cal Spas C-3000
  • Cal Spas Atlantic Series
  • Cal Spas Pacific Series

Common Causes

  • Sensor failed open (most common at 5+ years)
  • Sensor wire damaged or pinched
  • Connector at board corroded
  • Scale buildup insulating sensor from heater pipe
  • Control board sensor input fault (rare)

How to Fix It

  1. Power off at breaker.

    Hot tubs run 240V — power off at dedicated breaker.
    Use non-contact voltage tester to confirm power is off near heater terminals.

  2. Locate the sensor.

    Open equipment compartment.
    Sensor is a small probe clamped or strapped to the heater pipe.
    Two-wire cable runs to control board.
    Cal Spas typically uses one or two sensors (operating + high-limit).

  3. Inspect connector.

    Disconnect sensor at the board.
    Look for green corrosion or moisture.
    Use contact cleaner if dirty.
    Reseat firmly.
    Sometimes loose connector causes intermittent SnR.

  4. Test sensor with multimeter.

    Disconnect sensor.
    Multimeter on ohms.
    At room temp (~70°F), should read 8-12k ohms.
    Open circuit (OL display) = bad sensor.
    Very low ohms (under 1k) = shorted sensor.

  5. Replace sensor.

    Match part number on existing sensor.
    Cal Spas sensors are 25-60 USD via spa parts dealers.
    Mount new sensor against bare metal pipe — scale or paint blocks heat transfer.
    Plug into same connector at board.

  6. Confirm clip tight.

    Sensor clip must hold sensor firmly against heater pipe.
    Loose clip means sensor reads ambient air, not water temperature.
    Tighten clip if needed.
    Replacement clips available from same parts dealers.

  7. Power back on.

    Restore breaker.
    Spa boots, control board reads sensor.
    SnR should clear within seconds.
    If error returns, check connector again or replace sensor with confirmed-good unit.

Frequently Asked Questions

How do I tell which sensor is the operating vs high-limit?

Operating sensor is on the heater inlet (water flowing IN side); high-limit on the outlet.
Cal Spas wiring diagram shows specific positions.
If unsure, take a photo before disconnecting and consult the manual.