Tub is not heating to temperature and flashing a Ec message on the temperature screen.

just a guess but id say your temperature controller has failed and it went over temperature , the safety cut in to save the tub (heat suspended) could be anything in heating circuits from heat elements to temp probes

You have it in "Sleep" mode. Spa will not heat normally in this mode...

If the SL Message is Alternating with the Water Temp in the Display Screen (we call this "Flashing Sleep"), the Spa is Operating in the Sleep Heating Mode.

If the SL Message is ON Solid (Not Flashing) in the Display window of the panel, the Spa is Operating in the Sleep Heating Mode, but there is No current water temperature because the Spa is between Filter Cycles.

Between Filter Cycles, while in the Economy or Sleep Heating Modes, the Pump has not turned ON and the Last Water Temperature is not Current. To read the Current Water Temperature, either Change to Standard Heating Mode or turn On the Heating Related Pump, and wait at least 2 Minutes.

SL or SLP is one of the Modes you can program your spa into:
EC - Economy
ST/Std - Standard
SL/SLP - Sleep

It is advised you keep your spa in Standard mode. Push the Jets button then immediately push the light button. Each press of the light button will scroll between these three modes.

Good Luck

Check your filter cycles and switch spa into Standard Mode as you have it in Economy. (In Economy mode it will only heat during the filter cycles).
If the Ecn or Ec Message is Alternating with the Water Temperature on the Display, the Spa is Operating in the Economy Heating Mode.

If the Ecn or Ec Message is ON Solid (Not Flashing) on the Display, the Spa is Operating in the Economy Heating Mode, but there is No current water temperature because the Spa is between Filter Cycles.

Ecn or Ec is Alternating with Temp:
The Spa is Operating in the "Economy" (Ecn or Ec) Heating Mode.

The Water Temperature is Sampled Only during Programmed Filter Cycles. The Heater will Only operate and Heat up to Set Temperature during the Filter Cycles. The Water Temperature will probably drop Below Set Temperature between Filter Cycles. Other Heating Modes are Standard, Standard in Economy, and Sleep Modes.

Ecn or Ec is ON Solid (Not Flashing):
The Current Water Temperature is "Unknown" (- - - or - -) while in Economy or Sleep Mode.

Between Filter Cycles, while in the Economy or Sleep Heating Modes, the Pump has not turned ON and the Last Water Temperature is not Current. To read the Current Water Temperature, either Change to Standard Heating Mode or turn On the Heating Related Pump, and wait at least 2 Minutes.

Your spa is in Economy Mode:
Ecn or Ec MessageEcn or Ec Message

If the Ecn or Ec Message is Alternating with the Water Temperature on the Display, the Spa is Operating in the Economy Heating Mode.

If the Ecn or Ec Message is ON Solid (Not Flashing) on the Display, the Spa is Operating in the Economy Heating Mode, but there is No current water temperature because the Spa is between Filter Cycles.

Ecn or Ec is Alternating with Temp:
The Spa is Operating in the "Economy" (Ecn or Ec) Heating Mode.

The Water Temperature is Sampled Only during Programmed Filter Cycles. The Heater will Only operate and Heat up to Set Temperature during the Filter Cycles. The Water Temperature will probably drop Below Set Temperature between Filter Cycles. Other Heating Modes are Standard, Standard in Economy, and Sleep Modes.

Ecn or Ec is ON Solid (Not Flashing):
The Current Water Temperature is "Unknown" (- - - or - -) while in Economy or Sleep Mode.

Between Filter Cycles, while in the Economy or Sleep Heating Modes, the Pump has not turned ON and the Last Water Temperature is not Current. To read the Current Water Temperature, either Change to Standard Heating Mode or turn On the Heating Related Pump, and wait at least 2 Minutes.

Ecn or Ec Message
Ecn or Ec Message

If the Ecn or Ec Message is Alternating with the Water Temperature on the Display, the Spa is Operating in the Economy Heating Mode.

If the Ecn or Ec Message is ON Solid (Not Flashing) on the Display, the Spa is Operating in the Economy Heating Mode, but there is No current water temperature because the Spa is between Filter Cycles.

Ecn or Ec is Alternating with Temp:
The Spa is Operating in the "Economy" (Ecn or Ec) Heating Mode.

The Water Temperature is Sampled Only during Programmed Filter Cycles. The Heater will Only operate and Heat up to Set Temperature during the Filter Cycles. The Water Temperature will probably drop Below Set Temperature between Filter Cycles. Other Heating Modes are Standard, Standard in Economy, and Sleep Modes.

Ecn or Ec is ON Solid (Not Flashing):
The Current Water Temperature is "Unknown" (- - - or - -) while in Economy or Sleep Mode.

Between Filter Cycles, while in the Economy or Sleep Heating Modes, the Pump has not turned ON and the Last Water Temperature is not Current. To read the Current Water Temperature, either Change to Standard Heating Mode or turn On the Heating Related Pump, and wait at least 2 Minutes.

If the SLP or SL Message is Alternating with the Water Temperature on the Display, the Spa is Operating in the Sleep Heating Mode.

If the SLP or SL Message is ON Solid (Not Flashing) on the Display, the Spa is Operating in the Sleep Heating Mode, but there is No current water temperature because the Spa is between Filter Cycles.

Hope this helps.
US Parts Center

EC stands for Economy mode. This is a setting that tells the computer to check the temperature of the spa less frquently, as well as running fewer filter cycles. Spas should be set to EC while you are away on vacation or not planning to use it for a while

Your spa is in Economy mode. You have a basic Balboa Controller likely a Value Series.

If the Ecn or Ec Message is Alternating with the Water Temperature on the Display, the Spa is Operating in the Economy Heating Mode.
If the Ecn or Ec Message is ON Solid (Not Flashing) on the Display, the Spa is Operating in the Economy Heating Mode, but there is No current water temperature because the Spa is between Filter Cycles.