Raypak Pool Heater Sensor Failures [Solved]

When Raypak pool heater sensor failure occurs, you will get diagnostic readouts such as, “Sensor Failure’, “Sensor Open” or “Sensor Shorted”. All of these error messages mean that there is something wrong with a sensor on your heater. 

raypak pool heater sensor failure

But there are a few sensors your heater has. The Raypak 406a sensor failure can be of three different types. You need to take different measures to fix each of these sensor failures. The common Raypak heater sensor failures are:

  1. Temperature sensor failure
  2. Pressure sensor failure
  3. Roll-out sensor failure

Keep reading our Raypak sensor troubleshooting manual to fix any of these sensor failures that may be causing your heater to malfunction.

Raypak Pool Heater Sensor Failure [3 Easy Solutions]

Paying attention to the Raypak pool heater sensor failure code displayed on your screen is the first step.

  • SNS error code indicates temperature sensor failure.
  • PRS error message indicates pressure sensor failure.
  • And “rollout SW open” is visible on display when the roll out sensor is failing.

We will now take a detailed look at solving each of these sensor failures. We will explore the possible causes of these different sensor failures and how to solve them.

Note: Also read and know how to fix Raypak pool heater ignition failure.

1. Temperature Sensor Failure

There are two temperature sensors in a Raypak pool heater. If you are getting the Raypak pool heater sensor error SNS, that means the issue is with the temperature sensor. 

Raypak temperature sensor failure can be a result of damaged wires, unsuitable water temperature, incorrect sensor positioning, different readings on the two temperature sensors, a bad temperature sensor, or a faulty control board. Here’s what you need to do in each case.

i) Damaged Wires

If P1 has a loose or corroded connection it can cause an SNS pool heater sensor error. Critters can also chew away at the wiring connections.


Check the wires for damage and replace any if needed. Ensure that all connections are tightly secured.

ii) Unsuitable Water Temperature:

The range of water temperature needed is 36°F-110°F. If the water is above or below this range the SNS error will pop.


Adjust the thermostat to the required water temperature range. If the water isn’t getting to the temperature that you set, call in a professional technician to help you out.

iii) Incorrect Sensor Positioning

The sensor may produce a misleading reading if it is not fully seated in the JACO fitting on the header causing SNS error.


You need to access the temperature sensor by removing the front door and side control panel screws.

Lay the control panel forward and you can see the temperature sensor. Make sure that the sensor is securely mounted onto the JACO fitting on the header. 

iv) Different Readings

If the two temperature sensors are giving readings that differ from each other by more than 2 degrees you will get an SNS Raypak pool heater sensor error code.


Reset the heater. If the error still persists, you may have a damaged temperature sensor.

v) Bad Temperature Sensor

If you are getting the Raypak SNS code, your Raypak thermistor or temperature sensor may be damaged.


First, you need to test the thermistor to see if it needs replacement. With a multimeter, check the resistance of the temperature sensor.

Refer to the table below for the expected resistance value of the thermistor at different temperatures. If the reading you get is off by more than 10% of the value on the chart, the thermistor is faulty and it’s time for Raypak temperature sensor replacement.

Temperature (°F)405060708090100106
Temperature (°C)4.4 1015.621.126.732.237.841.1
Resistance261.1 199.0153.1 118.8 93.0 73.358.3 51.0
Resistance At Different Temperatures

vi) Faulty Control Board

If any of the above reasons aren’t responsible for Raypak SNS code, you have a faulty control board.


Contact Raypak customer care to send you a new control board or get information on which model to purchase. Get a local electrician to help you out.

2. Water Pressure Sensor Failure

Several things could have contributed to the Raypak pool heater water Sw open error.

Water pressure is the most notable. With low water pressure, the heater may only run for a few minutes before shutting off.


First, make sure all of your pool filters and skimmer are free of debris. Make sure your pump is turned on and the skimmer is full of water.

Check the location of the pump and ensure it is not far away from the pool. Adjust the pressure if it is more than 5 feet above or below the water level.

3. Roll Out Sensor Failure

Raypak rollout Sw open error can be caused by either a clogged-up and dirty heat exchanger or a faulty fusible link.


Take off the heater top to examine the heat exchanger. Remove any leaves or debris with a wet/dry vac, and look for signs of bird or rodent nests.

Examine the spaces between the tube coils using a flashlight. Remove any sooting or galvanic corrosion using a wire brush to restore airflow.

If the heat exchanger is looking good but the error persists, you need to replace the fusible link.


Why won’t my pool heater fire up?

Raypak ignition failure may be caused by a clogged pool filter. It is the most common cause of low water flow rate which is one of the main reasons why ignition failures occur.

Is Raypak the same as Rheem?

It’s the same unit, just with a new name badge. The parent firm is Raypak. They are one of the most effective heaters available today.

Do pool heat pumps use a lot of electricity?

A 100,000 BTU heat pump uses about 5 kilowatts per hour. The electricity required for a standard 100,000 BTU pool heat pump is around 5,000 Watts per hour. The national average for electricity is currently 13 cents per kilowatt-hour.

What is a comfortable pool temperature?

According to the World Health Organization, the safe and comfortable water temperatures in a swimming pool should be between 78 to 86° F. for persons participating in moderate activity in a pool.

Should I run my pool heater at night?

Because of the time and energy it takes to heat your pool at night, it is not recommended. To save money, heat your pool during the day and, if possible, use a solar blanket to keep the temperature consistent.


A modern-day pool heater will have a few sensors to ensure the safety of the unit. When you experience a Raypak pool heater sensor failure, follow the instructions above to get your heater working in no time.

Well, if you have any more queries, the comment box is free for you.

About William

William is the founder of Fireplacehubs.com. He has real life practical skills in fixing smoker & heating appliance issues. He loves to share his knowledge & helps others in fixing their appliances & saving their money. William firmly believes that anyone can repair his or her unit with the correct guidance & knowledge. See more at about us.

4 thoughts on “Raypak Pool Heater Sensor Failures [Solved]”

  1. For the “Sensor Failure” you say to reset the heater, but I don’t know how to do that. I’ve read the manual and there are several resets – default reset, resetting/clearing fault history, etc – can you pls explain what to do to reset the heater for a sensor failure when the temperatures are more than 2 degrees different?


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