This error message on a Sundance Spas made tub is called the watchdog error.
When a spa enters watchdog mode it will not leave without a full reboot.
This error can be caused most commonly by any of the following things. (and rarely multiple!)
- Bad boot up sequence or power fluctuation, this can be caused by a small “brown” out, or just unclean non-solid power.
Solution: Try turning off the spa for 1-2 minutes, then reboot. This allows ample time for the board to get a full reboot. If problem persists move to next.
- Temperature overheat, a dirty filter or low flow conditions. This cause will likely take 20-40 seconds to cause the watchdog error, and should show you other errors before kicking to watchdog, like FLO or OH. In some less common situations a failed circulation pump can overheat (pump gets very hot to the touch) and the heat will transfer up into the heater and cause it to overheat. If you see no other errors, or the watchdog error shows very quickly, move to other reasons. A failed or underperforming circulation pump should cause a FLO or FL1 error, but in some rare cases a bad flow switch will not report and your first clue something is wrong is the watchdog error (—-).
Solution: Remove filter (and any large debris) completely and run hot tub for a couple minutes, if problem resolves it may be time to deep clean your filter, or may be time for replacement. Remember 2 years is an average filter life.
If the circulation pump is the problem they are easy to replace, make a note if you need a 120v or a 240v, pump will have a label with voltage. Perform the “Bad temperature sensor” test below since a temperature sensor is much cheaper than a circulation pump.
- Bad temperature sensor, this is a relatively cheap part that can fail over the years. One easy way to sometimes confirm this part has failed is as follows: Have one person stand at the power for the spa, another person will stand at the spa control panel. When power is applied the person standing at the spa is looking for a reading of the temperature before the display goes to all dashes. (this can be very quick, this is why it usually needs two people) What the person is looking for is the temperature to display a very high temperature, usually over 110 degrees before it kicks to watchdog, if you see this behavior you most likely need a new temperature sensor.
Solution: Replace temperature sensor. There are different wire ends on the different sensors used through the years, the three different types can be found here. We have an instruction sheet that explains how to do this since it is an easy process, we have many clients that perform it themselves. Keep in mind this sheet was written for the “curled end” sensor. Good eyesight is useful as two of the connections are very small. Don’t be rushed, Don’t do it at dusk.
- Bad capacitors on circuit board, many capacitors supplied in electronics in the early 2000’s suffered from capacitor plague, this is often fairly easy to diagnose since you can visually inspect the capacitors and see if they have and “bulge” to them, they are usually located near the center of the board and kinda look like batteries soldered onto the board. Then ends should be perfectly flat and if they have a swollen appearance they are bad and can cause the watchdog error. It seems like cold weather or being shut off for a while (circuit board cools) are when capacitors really cause the watchdog error.
Solution: Replace board, we always recommend replacing the entire board since it is very easy to ruin a board by trying to desolder and replace the capacitors, it can be done, but it is much more reliable to just replace the part. For most users this often would require a service call, although if you are ok reading a wiring diagram or take some good pictures, it is a fairly easy job.