Topside control displays HL or HtL and spa shuts down; pumps may stop and heater is disabled.

Safety first: Turn off power at the GFCI breaker before opening any equipment area. Hot water and live electricity are dangerous.

• Check water level: Ensure the water level is above all skimmer openings and filter intakes. Top up if low.
• Remove and clean filter: Take out the Coast Spas filter cartridge. Rinse thoroughly with a garden hose from top to bottom. If the filter is more than 1–2 years old or pleats are collapsed, replace it.
• Bleed air from system: After a refill, air can be trapped. Loosen the union on the pump or heater slightly until water seeps out, then retighten. Some Coast Spas models have bleed valves on the pump—open briefly to purge air.
• Check circulation pump operation: Restore power and verify that the dedicated circulation pump (if equipped) is running and there is strong flow from the circulation return. If not running, the pump or its capacitor may be faulty.
• Reset the spa: Turn power off at the breaker for 5 minutes, then back on. If HL returns quickly, the high-limit sensor or heater assembly may be defective.
• Do not bypass safety devices: If the high-limit sensor is suspected faulty, replace it; never jumper or bypass it.