Jandy LXi 400,000 BTU Low NOx Pool and Spa Heater HLS Error Fix: High Limit Switch Tripped

Error code HLS on the Jandy LXi 400,000 BTU Low NOx Pool and Spa Heater means: High Limit Switch Tripped. The high limit thermostat detected water temperature exceeding the safe maximum — the LXi shut down to prevent scalding and heat exchanger damage; almost always caused by inadequate water flow (dirty filter, low pump speed, closed valves, scaled heat exchanger); let the heater cool, restore adequate flow, and restart; the high limit is a resettable thermal switch; if it trips repeatedly, investigate the root cause — do NOT bypass the high limit

The most successful fix is "Test and Replace High Limit Switch" (medium difficulty, ~60 minutes). Estimated DIY cost: $10-$25. HomeMD has 2 community-ranked fixes for this error.

This error is rated medium severity. It should be addressed soon, but your appliance may still function in a limited capacity.

Yes — the top-ranked community fix ("Test and Replace High Limit Switch") is rated medium difficulty and takes about 60 minutes. Tools needed: T20 Torx screwdriver, Multimeter, Needle-nose pliers.

DIY cost: $10-$25. Professional repair typically costs $150-$300. Many homeowners save money by trying the top-ranked community fix first.

The Jandy LXi 400,000 BTU Low NOx Pool and Spa Heater has 8 other known error codes, including: AFC (Airflow Current Fault), AGS (Air/Gas Switch Fault), CE (Communication Error), FE (Flue Exhaust Fault), FLO (Flow Fault — Insufficient Water Flow), and 3 more.