Hot tub FLO and flow error codes
Short answer
FLO means the control expects water moving through the heater and sees none, so it turns the heater off. Gecko's guide sets 18 gallons a minute as the minimum. Start with the filter, the water level, the valves and any air lock.
What you can check yourself
- Clean the filter, or replace it if it is worn.
- Check the water level and top it up to the line in your manual.
- Open any closed valves and jets.
- Purge an air lock the way your owner's manual describes.
- Reset the GFCI or breaker once. If it trips again, leave it off.
Where the owner's part ends
Anything else: turn off power at the breaker and call a technician.
Heaters, pumps, sensors and the control board sit on mains power next to water. Never bypass a sensor, a pressure or flow switch, or a high-limit to get a tub running: they are what stop it from overheating.
Why does a hot tub show a flow error?
Because the heater needs water moving past the element to carry the heat away, every control refuses to heat until it is sure water is flowing. How it checks depends on the system. Older packs and many brand systems use a pressure or flow switch in the plumbing: Sundance's 2016 manual says FL1 means the pressure switch did not close when jets pump 1 started. Balboa's M7 heaters use two temperature sensors instead and read a big gap between them as poor flow. Gecko's Y series heaters carry an electronic check called in.flo.
Whatever the sensor, the usual causes sit on your side of the cabinet: a clogged filter, a low water line, a closed valve, or air trapped in a pump after a refill.
Every flow code, system by system
30 codes
| Code | What it means | What to do |
|---|---|---|
| M016Also: HFLBalboa, M codes | Panel: The water flow is lowNot enough water is moving through the heater to carry the heat away. The heater waits about a minute and tries again. | Check first
Call if it keeps coming back after the checks. |
| M017Also: LFBalboa, M codes | Panel: The water flow has failedFlow through the heater stayed too low and the heater has been switched off. It stays off until you clear the message. | Check first
Call if it returns after the checks and one reset. |
| M033Balboa, M codes | Panel: Safety trip, pump suction blockageThe vacuum switch closed because of a suction problem or a possible entrapment. Not every spa has this switch. | Stay out
Turn off power and call for service. |
| HFLAlso: HL, HTR FLOW LOSSBalboa panel letters | Panel: Heater flow is reducedLow flow through the heater during heating; the heater retries after about a minute. Same fault as M016. Balboa's service manual lists HL as another panel's name for it. | Check first
Call if it keeps returning. |
| LFAlso: HTR FLOW FAILBalboa panel letters | Panel: Heater flow failedPersistent low flow: the heater is off but the rest of the spa runs. Same fault as M017. On Balboa's VL panels it shows after the fifth flow-loss message within 24 hours. | Check first
Call if it returns after the checks. |
| FLOGecko Y series, in.xe | No water flow detected while the main pump runs. Gecko's guide lists 18 GPM as the minimum flow. | Check first
Call if it persists; the next steps are inside the equipment bay. |
| FLOAlso: FLO - L01, FLO - L02Gecko in.k1000 | Panel: FLO conditionA no-flow condition. Gecko's own list says to check the filter, pump, blockage, air lock and water level. | Check first
Call if it persists. |
| NO FLOGecko in.k1000 | Panel: Persistent NO FLO, all offThe no-flow condition persisted and everything has been shut off. | Check first
Call if it returns after the checks. |
| CFLOGecko in.k1000 | Panel: No Flow conditionA no-flow condition. | Check first
Call if it persists. |
| FLCGecko in.k1000 | Panel: The pressure switch is closedThe pressure switch reads closed when it should not. | Technician Call for service. |
| FLOGecko MSPA, SSPA | No pressure at the pressure switch while the pump runs. A dirty filter or anything limiting flow can cause it. Packs from 1998 on switch the heater off. | Check first
Call if it persists after the checks. |
| FLCGecko MSPA, SSPA | The pressure switch reads pressure while the pump is off. | Technician Call for service. |
| E2Hot Spring 2026 | Panel: E2: NO FLOW-CHECK FILTERNo flow or a pressure switch error; the heater is off. The logo status ring flashes yellow. | Check first
Call if it keeps tripping. |
| Green and blue logo lights blinkingHot Spring 2026 | Panel: Ready and Power blinkingThe spa does not heat but jets and light work: the integrated pressure switch is open or the circulation pump's thermal cut-off tripped. | Check first
Call if the heater trips often. |
| *====Hot Spring Hot Spot | Panel: *==== with POWER and READY flashingNo heat while jets and light work: the pressure switch is open, or senses flow with the jet pump off. | Check first
Call if it trips often. |
| =====Hot Spring Hot Spot | Panel: ===== with POWER and READY flashingThe pressure switch is closed when it should be open. | Technician Contact an authorized service technician. |
| FLOHot Spring FreeFlow | The control expects flow and sees none. | Check first
Call if it persists. |
| Orange and gray logo lights blinkingCaldera 2026 | Panel: Ready and Power blinkingNo heat while jets and light work: the integrated pressure switch is open or the circulation pump's thermal cut-off tripped. | Check first
Call if the heater trips often. |
| FL--1Jacuzzi 2017 | Panel: FLOW ERROR OPENThe flow switch is stuck open, the filter is very dirty, or air is trapped at the circulation pump intake. The heater and possibly jets pump 1 stop. | Check first
Contact your Jacuzzi dealer if it persists. |
| FL--2Jacuzzi 2017 | Panel: FLOW ERROR CLOSEDThe flow switch is stuck closed. The heater and possibly jets pump 1 stop. | Technician Contact your Jacuzzi dealer. |
| Code 16Jacuzzi 2025 on | Panel: Heat Low FlowLow water flow inside the heater. | Check first
Contact your dealer if it persists. |
| Code 17Jacuzzi 2025 on | Panel: Failed FlowFlow inside the heater has failed. | Check first
If the filter is already new, contact your dealer. |
| FL1Sundance 2016 | Panel: FL1 (flashing)The pressure switch did not close when jets pump 1 started: flow is blocked or the switch failed. The heater is off. | Check first
Contact your Sundance dealer if it persists. |
| FL2Sundance 2016 | Panel: FL2 (flashing)The pressure switch is stuck closed. The heater is off. | Check first
Contact your Sundance dealer if it persists. |
| Code 16Sundance 880, 2025 | Panel: Heat Low FlowThe water flow through the heater is low. | Check first
Call if it keeps returning. |
| Code 17Sundance 880, 2025 | Panel: Failed FlowThe water flow has failed. | Check first
Call if it returns after the checks. |
| HFLAlso: HL, HTR FLOW LOSSVita Spa 2026 | Panel: The water flow is lowA heater flow problem: the heater stops while the spa keeps running. A plugged filter or low water can cause it. | Check first
Contact your dealer if it persists. |
| LFAlso: HTR FLOW FAILVita Spa 2026 | Panel: The water flow has failedA persistent flow problem; the heater stops. | Check first
Contact your dealer if it persists. |
| FLONordic, Gecko era | No water pressure while the pump runs. | Check first
Call if it persists. |
| FLCNordic, Gecko era | A pressure switch problem. | Technician Call your dealer. |
What is the difference between FL1 and FL2?
FL1 says the switch sees no flow when it should; FL2 says it sees flow when it should not. The first is usually a water problem you can check. The second means the switch is stuck closed, which no amount of filter cleaning will fix. Jacuzzi's 2017 J-300 manual draws the same line between FL--1 (flow switch open) and FL--2 (flow switch closed), and Gecko between FLO and FLC.
How do you fix a FLO error?
Work through the water side first, with the power off where your manual says so. Jacuzzi's 2017 J-300 manual is a good example of a maker's method: power off, water above the jets and below the lowest pillow, a clean filter, then purge air by holding a running garden hose over the filter fitting for 30 seconds. Use your own manual's steps for your tub.
More detail: how to clean a hot tub filter, when to replace it and weak jets.
Why does the flow error come back after I clear it?
Because the cause is still there and the control keeps count. On Balboa's VL panels a low-flow warning that repeats five times in 24 hours turns into LF and the heater stays off until you clear it. Gecko's in.k1000 escalates a lasting FLO to NO FLO and shuts everything off. If the filter, water and valves are right and it still returns, the switch, sensor or pump needs a technician.
Common questions
Can I use my hot tub with a FLO error?
The heater stays off until flow is back, and on some systems the jets stop too. Fix the cause rather than running it. Never bypass a pressure or flow switch to make the code go away.
Can a dirty filter cause a FLO error?
Yes. Gecko's MSPA service manual names a dirty filter, or anything limiting flow in the pipes, as a cause of FLO, and every maker's flow checklist starts with the filter or the water level.
What do FLO-L01 and FLO-L02 mean?
Gecko's in.k1000 keypad list groups FLO-L01 and FLO-L02 with FLO as a flow condition and gives the same checks: filter, pump, blockage, air lock and water level. It does not explain the suffix, so treat them like FLO.
Should I take the filter out to clear a flow error?
No. American Whirlpool's manual says running the spa without filters is for testing only and never for use. Clean or replace the filter and put it back.
What is the difference between FLO and FLC?
FLO is the switch reporting no flow with the pump running. FLC is the switch reporting flow or pressure with the pump off, which means the switch itself is stuck. FLC needs a technician.
Sources
19
- Balboa TP400/TP600 user guide (40940_N), panel messages
- Balboa troubleshooting and service manual for EL/VS systems
- Getaway Hot Tubs owner's manual, 2026 (Master Spas)
- Balboa VL401 user guide (40789_G), diagnostic messages
- Gecko troubleshooting guide, Y series and in.xe (9919-101313-D)
- Gecko in.k1000 techbook, error messages
- Gecko MSPA-1-AX spa pack service manual
- Hot Spring Highlife Collection owner's manual, 2026
- Hot Spring Hot Spot Collection owner's manual, 2026
- Hot Spring FreeFlow Collection owner's manual, 2026
- Caldera Spas Utopia Series owner's manual, 2026
- Jacuzzi J-300 owner's manual, 2017
- Jacuzzi J5 owner's manual (rev A)
- Sundance Spas 680 Series owner's manual, 2016
- Sundance Spas 880 Series owner's manual, 2025 (rev E)
- Vita Spa owner's manual, 2026
- Nordic Hot Tubs manual with Gecko equipment, 1999 to 2008
- American Whirlpool owner's manual, 2026
- Gecko Y series techbook
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