Display shows OH or OHH; spa shuts down and may run jets to cool water; water feels excessively hot

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

• Verify actual temperature: Use a separate thermometer to confirm water temperature. If water is truly very hot (>108°F / 42°C), leave the cover open and allow it to cool naturally.
• Check for low flow: Remove the filter cartridges from the Bullfrog filter well. Rinse them thoroughly with a garden hose from top to bottom. If they are old or collapsed, replace with genuine Bullfrog filter cartridges.
• Inspect circulation pump: With power ON (after water cools), observe if the dedicated circulation pump (if equipped) is running when the spa is in heat/filtration mode. Listen for humming without water movement, which indicates a seized pump.
• Bleed air from system: After any drain/refill, loosen the pump union on the suction side of the primary jet pump and the circulation pump slightly until water seeps out, then retighten. This removes airlocks that can cause low flow and overheating.
• Check for closed valves: Ensure all slice valves around the pumps and heater are fully open (pulled up). Closed valves will starve the heater of flow.
• Reset the spa: Once water is at a safe temperature and flow is restored, turn the breaker OFF for 2–3 minutes, then ON. Monitor for OH returning.

If OH recurs quickly with good flow and clean filters, the heater relay may be stuck ON or the high-limit sensor may be faulty. In that case, discontinue use and have a Bullfrog technician inspect the control pack and heater assembly.