HL error appears and spa stops heating; pumps may continue to run.

Safety first: Turn off power and allow the spa to cool before working on the heater area.

• Clean filter and check flow: Remove and clean the filter cartridge. Ensure all valves are open and that there is no visible restriction in the plumbing.
• Bleed air: Loosen a union near the heater or use the bleed screw (if present) to release trapped air until water flows steadily.
• Reset system: After restoring flow, turn power back on and see if the HL code clears automatically. Some models may require a power cycle.
• Replace sensor if recurring: If HL continues to trip despite good flow and normal temperatures, replace the high-limit sensor with a compatible Aquavia part.