Display shows OHH, spa immediately shuts down heater and often pumps, may not reset until power is cycled.

Safety: Turn off power at the breaker. Do not attempt to bypass safety sensors or relays.

• Allow full cool-down: Leave the cover open and let the spa cool completely. Once water is below 95–100°F, restore power and see if the error clears.
• Inspect heater tube: With power OFF, open the equipment bay and inspect the stainless heater tube on the QCA Spas control pack for discoloration, scorching, or melted insulation—signs of overheating.
• Check for stuck heater relay: After restoring power, listen for the heater relay clicking on/off. If the heater indicator is on even when the set temperature is below water temperature, the relay may be stuck closed and the control board may need replacement.
• Replace sensors if suspect: If OHH recurs despite good flow and normal operation, replace both the temperature and high-limit sensors on the heater manifold as a matched set.