Display shows COd or COLD, and the spa will not start normal heating until the temperature rises.

Safety first: Ensure all plumbing is thawed before operating the spa.

• Gradual warm-up: Allow the Everlast heater and pumps to run as programmed. COd should clear as the water temperature rises.
• Insulate: Keep the Everlast cover closed and consider adding a floating thermal blanket to speed up heating.
• Sensor check: If COd persists in moderate temperatures, test the temperature sensor and replace it if it reads abnormally low.