Display shows OH or OHH, spa shuts down, pumps may run briefly then stop, water feels very hot near or above set temperature.

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

• Remove spa cover and cool water: Leave the cover open to allow heat to escape. Do not add cold water directly to very hot acrylic to avoid thermal shock; instead, allow gradual cooling.
• Check filters and flow: Once cooled and power is OFF, remove and clean or replace the filter cartridge. Inspect for obstructions at the skimmer and suction fittings.
• Verify pump operation: Restore power and observe that the low-speed of the main pump or dedicated circulation pump runs continuously during heating. If the pump does not run, hums, or trips the breaker, it may be seized or failing.
• Inspect sensors on heater tube: Locate the temperature and high-limit sensors threaded or clamped to the stainless-steel heater tube. Check for loose connections or corrosion. If OH recurs with good flow and normal water temperature, replace the high-limit sensor (and often the temperature sensor as a pair).
• Check for trapped air: After draining/refilling, bleed air from pump unions to ensure water fully fills the heater tube; air pockets can cause localized overheating.