Display shows OHH and spa immediately shuts down heater and pumps; often accompanied by very hot water in equipment bay.

Immediate safety: Turn OFF power at the main breaker. Do not reset repeatedly; risk of scalding and equipment damage.

• Allow full cool-down: Leave the spa powered OFF with the cover open until water temperature is safely below 35–38°C (95–100°F).
• Inspect for melted or scorched components: Remove the equipment access panel and visually inspect the RivieraPool heater tube, wiring, and control pack for discoloration, melted insulation, or burnt smell. If present, do not power the spa; contact a technician.
• Check filters and valves: Ensure filters are clean and all slice valves are fully open to restore proper flow.
• Check high-limit sensor: The RivieraPool high-limit sensor is usually mounted on or in the heater tube. Inspect its wiring and seating. Replace if brittle, cracked, or corroded.
• Heater relay test (advanced): With power OFF, disconnect heater leads from the control board. Restore power and run the spa without the heater connected. If OHH no longer appears, the heater or relay may be at fault. This test should be performed only if you are comfortable working around electrical equipment.
• Final step: If OHH recurs after sensor replacement and flow correction, the RivieraPool control board (heater relay) or heater assembly likely requires replacement by a qualified spa technician.