Hot Tub Repairs Cheat Sheet – Your Crash Course in Spa Repair

Hot tubs these days are pretty advanced compared to the standard models that hit the market decades ago.

With advanced systems and new technology, it’s never been more important to have a hot tub repairs cheat sheet.

Modern advancements or improvements have made it easier for homeowners to troubleshoot their spas themselves.

However, depending on the repair needed, you may not be able to DIY the repair yourself,  but with a little know-how, you should be able to confirm what the repair or service issue may be before scheduling a service appointment.

Most issues can be identified simply by reading the topside control panel.

To save you from hunting down your manual or scouring the web, we’ve created an easy cheat sheet for the most common hot tub repairs and their associated codes.

Let’s get into it!

hot tub repair - error codes

Basic Hot Tub Repairs Cheat Sheet

One of the first ways your spa will communicate a problem with you is by flashing an error code on your control panel.

Knowing what these error codes mean and the steps you can take to mitigate the problem can be crucial in getting your spa back up and running sooner rather than later.

Here are some of the most common codes and exactly what to do when they appear.


If you’re seeing this error, it means that the temperature of the water is 20 degrees below the temperature you’ve set.

When this happens, the low-speed pump, circulation pump, and heater will come on and stay on until the water temperature reaches within 15 degrees of the set temperature.

Typically, this happens after you drain and refill your spa with fresh, cool water from your garden hose spigot.

If you see this error and you just refilled your spa, give it time to come up to temperature.


This code indicates that there is a potential freeze condition detected, meaning your water is at 55 degrees.

When this happens, pump 1 activates, and then pump 2 activates after 10 seconds. Then, both pumps stay on for a minimum of 11 minutes or until the danger of freezing passes (65 degrees).

Typically, this happens after you refill your spa with ice-cold water from your garden hose spigot.

If that’s the case, give your spa time to bring your water back up to temperature and keep a close eye on your control panel.

The ICE message could also appear if your spa’s heater shuts down for a long enough period of time that your water temperature drops to 55 degrees.

If you have not just added fresh water to your spa and this error occurs, you will want to investigate further.

If your water is not being heated properly, it may point to an issue with your heating element.

To verify your heating element may be the issue, open the control panel on your spa and inspect your heater.

The element of your heater is always exposed to the water in your spa, which can lead to corrosion or scale build-up over time.

This is especially possible if your water has been left improperly balanced too often or for extended periods of time.

If you notice any signs of damage to your heating element, it may be time for a new one. But before making the purchase, schedule a service appointment to have the professionals take a look.

It could be possible there’s another issue looming on the horizon that may not have been so obvious.

Your service technician will be able to diagnose the issue, make recommendations, or repair the issue for you.

SN3 (sensor 3)

This means that your heater is deactivated or the temperature sensor is not working as expected.

More often than not, this would mean you have a bad temperature sensor.

However, before you go ahead and replace the sensor, it’s a good idea to check your connections where the sensor attaches to the PWA (printed wiring assembly).

If you have a loose connection, you may be able to tighten it and get your sense working normally again.

However, if this doesn’t work, your next step would be replacing the sensor, which should always be done by a certified professional, especially if your hot tub is still under warranty.

Remember, it’s never safe to use your spa if your system is unable to properly read the temperature.

If you’re experiencing error codes regarding your water temperature, keep everyone out of the water until the issue has been solved.

SN1 (sensor 1)

This error code is another one that relates to your heater.

SN1 signals that your heater is deactivated or that the hi-limit sensor is not working as expected.

Typically, this would mean you have a bad hi-limit sensor, and it needs to be replaced. This issue is quite rare, so if this error has occurred, you should take some extra steps before replacing the sensor.

Just like the issue above, you’ll want to check the connections where the sensor attaches to the PWA.

After ensuring they are properly connected, take a moment to check that the sensor probe is inserted completely into the heater thermowell.

If everything is in order, you’ll want to get your sensor replaced before using your spa again.

 – – – –

If you’re seeing a link of dashes, this error is known as the watchdog message.

Four dashed lines mean your hot tub is deactivated. Essentially, this means that the PWA thinks the spa temperature is 120 degrees F.

This error is typically caused by a bad temperature or hi-limit sensor. However, it can also be the result of a number of other issues, so it requires some troubleshooting to determine the root cause.

This could also be the result of an issue with the:

  • PWA
  • Control panel
  • Transformer

Apart from that, this could also appear if your filters are clogged, your F1 fuse is blown, or your spa is experiencing electrical issues.

In fact, if you leave an ICE, SN3, SN1 or FLO message uncorrected long enough, the – – – – message will surface.

To DIY this repair, you can try checking your connections and cleaning your filters.

However, if this fails to solve the problem, you’ll want to schedule a service appointment for a certified technician to diagnose and repair your spa.

Watch this short video for a crash course in cleaning your hot tub filters:

The Many Faces of FLO Message


Much like the SN errors above, FLO is another code that has different variations.

There are 3 variations in the type of FLO message that can show up on your control panel:

  1. Flashing FLO
  2. Solid FLO
  3. Solid FLO2

Flashing FLO message

Typically, this indicates that the circulation pump should be on and there should be water flowing, yet the system is not detecting any.

This can be caused by a:

  • Soiled or dirty filter
  • Plugged circulation pump
  • Bad circulation pump
  • Bad flow switch
  • Bad PWA.

If you leave a flashing FLO message uncorrected long enough and the water temperature ends up dipping below 55 degrees, you could end up with an ICE message alternating with the FLO message.

This is quite common in the winter months when a soiled or dirty filter is left unattended.

To diagnose and repair this issue, clean your filters and inspect your circulation pump.

If you’re able to get your water circulating once again, it may be a good plan to do a line flush to clear out any lingering debris that may have occurred in your circulation system.

However, if you’ve completed these steps and you’re still unable to get your water circulating, it’s time to schedule a service appointment.

Solid FLO

More often than not, this indicates that the circulation pump should be off and the system is detecting a closed flow circuit.

This message disables all spa functions, including the heater, so it’s crucial to get it troubleshooted and fixed as soon as possible, especially if it’s winter.

The most common cause of this is a shorted flow switch, which could be the result of hair or debris keeping the flow switch paddle closed.

However, it could also be a shorted circulation pump circuit or a bad PWA.

Solid FLO2

Typically, this error message indicates a closed flow switch circuit upon startup.

This message disables all spa functions except the ability of the spa to freeze protect itself. The problem must be corrected to clear this error code.

The most common issue causing this error code is a bad flow switch. However, it could also be a shorted circulation pump circuit or a bad PWA. Before considering replacing the witch, confirm your wiring.

It’s also possible hair or debris kept the flow switch paddle closed when it powered down.

Sometimes if you re-boot the system, the FLO2 message may go away, but it usually comes back within a 24-hour period.

Alternatively, the control panel may read a solid FLO message first when you power up your spa and then revert to a solid FLO2 message.

Heat & Flow

There can be a condition in your spa where heat and flow are working side by side to shut down the system.

When this happens, an error message OH (overheat) appears on your control panel, which often means the heater is deactivated.

If the hi-limit sensor reads a temperature of 116 degrees or more or if the temperature sensor reads 110 degrees or more, it can signal an overheat message.

When this error occurs, the circulation pump will activate for a minimum of 6 minutes or until the temperature has dropped to 106 or less.

Most times, the OH message is caused by a dirty or soiled filter or obstruction of water flow through the heater.

If this is the case, you might see the OH msg followed by the FLO message alternating on your control panel.

It can also be caused by a bad temperature sensor or a bad hi-limit sensor. If the OH message is left uncorrected long enough, the watchdog message will appear.

To troubleshoot this yourself, clean your filters and inspect your heater for any blockages. If this doesn’t work to clear the error code, schedule a service appointment.

Hot Tub Repair in Winnipeg

Whether you’ve come face to face with any of these error codes and can’t seem to clear them up, or you’re struggling with other issues with your spa, the experts at Aqua-Tech are here to help.

Our team of certified technicians are well versed in the many error codes your spa may display and can help get your spa back up and running in no time.

Contact us today, or request an appointment online.


Related Articles

Yellow and blue kitchen design

Too Many Cooks in the Kitchen!

Do you like your kitchen? Do you feel inspired when you walk into your kitchen? Is it the heart of your home? Do you pour over magazines and computer images of beautiful kitchens and wonder “what would it be like to have a kitchen like THAT?” YOU can have a kitchen “like THAT”…did you know that ? It’s true! And Aqua-Tech can help make it happen.

Read More »
PDC Swim Spa

Waking Up Your Water Retreat: A Guide to Re-opening Your PDC Hot Tub or Swim Spa

As the season shifts and the chill of winter fades, it’s time to think about awakening your swim spa or hot tub from its seasonal slumber. This article is crafted for those who winterize their water retreats, guiding you through the essential steps to breathe life back into your spa. Whether you own a hot tub or swim spa, the process of reopening is crucial for ensuring your equipment runs smoothly and is ready to offer the relaxation and enjoyment you’ve missed during the colder months. We’ll cover everything from cleaning and inspecting to filling and balancing, ensuring your spa is Spring ready.

Read More »