Display shows OH or OHH and spa shuts down; water may feel very hot near heater or in footwell.

Safety first: Turn off power at the GFCI breaker immediately. Do not use the spa until the cause is identified. Very hot water can cause burns.

• 1. Remove spa cover and allow cooling: Leave the cover open to let heat escape. Verify water temperature with a separate thermometer.
• 2. Check water level and filter: Confirm proper water level. Remove and thoroughly clean or replace the Sundance MicroClean filter. A restricted filter can cause localized overheating at the heater.
• 3. Inspect circulation: After the water cools below 104°F (40°C), restore power and observe water movement from the circulation return. If there is no visible flow, the circulation pump may have failed.
• 4. Reset high-limit (if equipped): Some older Sundance models have a manual high-limit reset button on the heater. With power OFF and water cooled, press the red reset button until it clicks.
• 5. Monitor for reoccurrence: If OH returns quickly after reset, shut power OFF and do not continue to run the spa. This may indicate a stuck heater relay or faulty sensor.
• When to call a technician: Overheat faults can be dangerous. If cleaning the filter and confirming circulation do not resolve the issue, have a spa technician test the high-limit sensor, heater relay, and circulation pump.