7 Things Your Hot Tub is Trying to Tell You [Error Codes]

Have you ever gone out to your spa for a relaxing soak only to find an error code on your topside display? Nothing ruins an evening faster than cold hot tub water.

Fortunately, these error codes can help you pinpoint faults with the spa. Here are the 7 most common codes and what to do when you see them.

FLO

As you may have guessed, the spa has a flow problem. When heat is called for, the computer cannot detect pressure in the heater (little or no flow).

If you have recently drained and refilled the tub, an air pocket in the plumbing could be to blame. Try purging air from the plumbing by loosening, then retightening one of the pump unions. This will allow air to escape, often restoring full functionality.

If that doesn’t do the trick, try removing the filter(s). Very often dirty filters will trigger this error.

If the pump is not running and should be, have a technician test the pump. Any pump that gets the correct voltage should run.

FLC

This is actually the exact opposite of FLO – when you turn off the pump, the heater still detects pressure. This problem is usually associated with the pressure switch on the heater being out of calibration.

If you have recently worked on the spa, double-check that all plumbing valves are fully open. Additionally, try turning the pump off and on a few times to see if the condition resolves itself.

If the error doesn’t go away, a spa tech can either re-calibrate or replace the pressure switch.

HL

A high temperature (usually over 115°) in the heater tripped this code. This could be due to a lack of flow, a temperature sensor failure, or circuit board failure.

The first thing to do is power down the spa, remove the filters and open all of the jets. Turn the spa back on and watch the topside controller. If the error does not come back, clean (or replace) the filters and reinstall them.

If the error won’t go away, a technician should examine the temperature sensor or circuit board for fault.

Std or St, Ecn or Ec, SLP or SL

Good news, these are not error codes at all! These are operational codes, meaning Standard, Economy, and Sleep.

To switch between modes, press either the temp up or temp down button followed by the light button (or mode, if applicable).

Pro Tip: Leave your tub in Standard Mode if you use it regularly, reserving economy and sleep as “vacation” modes. This will keep your hot tub up to temp and ready to go anytime you’re ready.

SnA or SA, Snb or Sb

Houston, we have a sensor problem. In this case, either Sensor A or Sensor B, mounted on the heater, is not working.

With the spa powered down, unplug and re-plug the sensor into the circuit board about 5 times. Many times this will resolve any connectivity issues. If that does not resolve the problem, replace both sensors.

SnS or Sn

Take a note of how this error is displaying: is it alternating with the water temperature, or simply flashing?

Alternating with water temperature indicates that one sensor is reading a different temperature than the other. In this mode, the system will monitor the sensors for an hour, at which time the problem will resolve itself, or, Sn(S) will flash without the temperature.

When only Sn(S) flashes, the system has confirmed the sensors to be “out of sync” with each other. At this point, replacing both sensors, or having a technician inspect the system is in order.

drY or dY

Another flow-related issue, the heater does not have enough water in it to activate. Ensure the spa is full of water, and that the pump feeding the heater is working. Once you have resolved the problem, restarting the spa will get rid of the error code.

Key Takeaway

Do you notice how flow seems to be the overarching theme in most of these error codes? Here are some basic steps to ensure proper water flow:

1. Check for low water levels. Water should be at least 3” higher than the highest jet (excluding neck jets).
2. Check for blocked foot-well intakes or a blocked skimmer.
3. Check for a dirty filter. Sometimes hopelessly clogged filters will look clean and usable. Get in the habit of rinsing the filter weekly, and deep cleaning at every water drain and refill. For best performance, replace your filters yearly.
4. Open all the jets. Too many closed jets will reduce flow to the point where error codes start popping up.
5. Check for any closed or partially closed shut-off valves in the plumbing. Sometimes, broken valves may look open when they’re really partially or fully closed.
6. Make sure the pump related to the heater is primed and running. Priming the pump is as simple as carefully loosening one of the pump unions and letting water trickle out for about 5 seconds.

Error codes can be tricky, but with a little patience and Technical support, you can be back in hot water in no time! Don’t see your error code listed? Check out our How-to guide for a more expansive list.

Do you have a problem you just can’t figure out? Leave it in the comments below.