Display shows COd or COLD, and the spa will not start a normal heating cycle.

Safety: Protect the spa from freezing damage.

• Verify water temperature: Use a separate thermometer to confirm the actual water temperature.
• Allow freeze protection to run: The spa may automatically run pumps to prevent freezing. Do not shut off power unless you are winterizing the spa.
• Check sensors: If the water is not actually very cold but COd displays, inspect and test the temperature sensor for out-of-range readings.
• Insulate equipment bay: In very cold climates, ensure the cabinet is closed and insulated to help the spa warm up.

Once the water temperature rises above the freeze threshold, COd should clear automatically. Persistent false COd may indicate a faulty temperature sensor.