Display shows OH or OHH, spa shuts down and may run pumps briefly to cool, water feels very hot.

Safety: Do not use the spa when an OH/OHH condition is present. Turn off power at the breaker and allow water to cool below 100°F (38°C) before working.

• Remove cover and let spa cool: Take off the cover to allow heat to escape. Verify that the water is not above the set temperature once cooled.
• Check for low flow: Confirm that the filter is clean and the circulation pump is running. Follow the same filter and air‑bleeding steps as for FLO errors.
• Inspect temperature sensor placement: Locate the temperature sensor in the heater tube or sensor well. Ensure it is fully inserted and not loose or hanging out of the water stream.
• Power cycle the spa: After the water has cooled, turn power back on and monitor the temperature reading. If the heater continues to run past the set temperature, the heater relay on the control board may be stuck closed.

If OH returns quickly or the spa heats well beyond the set point, disconnect power and contact a technician to test the heater relay and replace the control board or sensor as needed.