Display shows HL or HLo and spa stops heating and may shut down pumps; water may or may not feel hot.

Safety: Turn off power at the GFCI before opening the equipment bay. Do not run the heater without proper water flow.

• Step 1 – Reset power: Turn off the breaker for 5 minutes, then turn it back on. If HL clears and does not return, it may have been a temporary condition.
• Step 2 – Bleed air from system: Open the equipment compartment. Loosen the union fittings on the heater or pump slightly until water seeps out to release trapped air, then retighten. Restore power and run the pump on low speed to purge air.
• Step 3 – Clean or bypass filters: Remove Catalina filter cartridges and hose them off thoroughly. Run the spa briefly without filters to see if HL returns. If the code disappears, replace the filters.
• Step 4 – Check circulation pump: Confirm the circulation pump (if equipped) is running smoothly and not noisy or hot to the touch. Poor flow can cause localized heater overheating and HL trips.
• Step 5 – Inspect high-limit sensor: Locate the high-limit sensor on the heater tube of the Catalina control pack. Check for loose plug, corrosion, or damaged cable. If HL persists and flow is good, replace the high-limit sensor.

Call a pro if HL returns immediately after reset or if you see melted wiring or a deformed heater tube.