Jandy LXi 400,000 BTU Low NOx Pool and Spa Heater FLO Error Fix: Flow Fault — Insufficient Water Flow

Error code FLO on the Jandy LXi 400,000 BTU Low NOx Pool and Spa Heater means: Flow Fault — Insufficient Water Flow. The flow switch is open indicating insufficient water flow through the LXi heater — the heater will not fire without confirmed flow; causes include pump not running or at insufficient speed, dirty pool filter, closed isolation valves, heater bypass valve opened too far, blocked heat exchanger, or defective flow switch (paddle-type); verify pump operation, clean filter, fully open heater isolation valves, adjust bypass valve

The most successful fix is "Test and Replace Flow Switch or Clear Heat Exchanger Blockage" (medium difficulty, ~60 minutes). Estimated DIY cost: $10-$20. 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 Flow Switch or Clear Heat Exchanger Blockage") is rated medium difficulty and takes about 60 minutes. Tools needed: T20 Torx screwdriver, Multimeter, Bucket, Garden hose.

DIY cost: $10-$20. Professional repair typically costs $200-$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), GV (Gas Valve Fault), and 3 more.

Error code FLO also appears on 2 other Jandy models: JXi 260 260,000 BTU Pool Heater with High Efficiency and Digital Temperature Control, JXi 400,000 BTU Pool and Spa Heater with Digital Temperature Control. The fix may vary by model, so check each model's specific page for tailored repair steps.