What does the Freeflow Spas error code HL mean?

Excessively hot water

The system has shut the heater off because the temperature at the heater has reached 122°F (50°C). DO NOT ENTER THE WATER. Remove the spa cover and allow the water to cool down, then shut power off and power your spa up again to reset the system. If spa does not reset, shut off the power to the spa and contact your local dealer.