Hot Tub Error Code Guide
FLO / FLC, Flow Error
UrgentThe control system doesn't detect adequate water flow through the heater, so it shuts heating off to protect the element.
Call 385-588-7757 for Fast RepairWhat Does FLO / FLC Mean?
FLO (also shown as FLC, FLOW, FL, FL1, or FL2 depending on the brand) means the control system isn't sensing enough water flow through the heater chamber. To protect the element from dry-firing, the system disables the heater. The spa may cool down, jets can weaken, and the display flashes the code until flow is restored or the fault clears.
It's one of the most common — and most commonly misdiagnosed — hot tub codes. Owners often assume they need a new heater or pump, when the real cause is usually a restriction or a cheap flow switch.
Also searched as: FLOW, FL, FL1, FL2, FLC, flow error hot tub.
Most Common Causes
- Dirty or clogged filter — restricts flow more than any other single item
- Low water level letting the skimmer pull air
- Airlock after a drain and refill (trapped air in the pump or heater loop)
- A valve left partially closed after service
- A failing circulation pump (common on 24/7 low-flow pumps)
- A faulty pressure or flow switch reading 'no flow' even when water moves
What You Can Safely Check First
- 1
Remove and thoroughly rinse the filter; if it's old or chemically saturated, replace it
- 2
Top off the water so it covers all skimmer openings
- 3
After a recent refill, bleed air from the pump — loosen the pump union slightly until water pushes the air out, then retighten
- 4
Confirm any valves are fully open
- 5
If the code clears with a clean filter and proper level, you're done; if it returns, the flow switch or circ pump likely needs testing
Brand-Specific Notes
Bullfrog spas frequently throw FLO when JetPak plumbing or filter restriction lowers circulation pressure. Sundance and Balboa systems may show FL1/FL2 variants tied to circulation vs. jet-pump flow. Hot Spring spas can flash related codes as the SilentFlo circulation pump wears out. The failing component differs by platform, which is why brand-specific diagnosis saves money.
How Urgent Is It?
Don't just keep resetting a FLO code — running a heater without flow destroys elements and trips high-limits. In winter, a spa that can't circulate is also a freeze risk, so treat a persistent FLO code as urgent November through March.
FLO / FLC FAQs
Can I still use my hot tub with a FLO error?
Not for heating — heating is disabled by design. Some jet functions may work, but in a Utah winter a non-circulating spa is at freeze risk, so a persistent FLO code should be treated as urgent.
How much does fixing a FLO error cost?
Cleaning a filter or bleeding an airlock is free if you do it yourself. If it's a part, professional diagnosis usually identifies a $40–$80 flow switch, a circulation pump issue, or a simple airlock — a wide range, which is exactly why guessing wastes money.
Still Seeing FLO / FLC?
Send us your spa brand and the code, we'll diagnose the root cause and bring the right parts.
Other Hot Tub Error Codes
FLO / FLC on your display? Let's fix it right.
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