Display shows OH or OHH and spa shuts down; water feels very hot.

Safety first: Turn off power at the breaker immediately. Do not use the spa until the cause is identified.

• 1. Remove spa cover: Allow heat to escape and let the water cool to below 100°F (38°C) before further testing.
• 2. Clean or remove filter: Take out the filter cartridge and rinse thoroughly. Run the spa briefly without the filter once power is restored to see if OH returns.
• 3. Check pump operation: With power restored and water cooled, verify that the circulation pump and jet pump(s) run when called for. If the heater is on without water movement, overheating will occur.
• 4. Inspect for stuck relay: If the heater indicator shows ON even when the spa is at or above set temperature, the heater relay on the control board may be stuck closed.
• 5. Verify sensor placement: Ensure the temperature sensor is fully inserted in the heater tube or well and not hanging loose in the equipment bay.

If OH recurs, disconnect power and contact a spa technician. Overheating can damage plumbing and pose a safety risk if not corrected.