Jacuzzi / Sundance · Jacuzzi and Sundance spas with LED or LCD panelsFix soon

FLO on a Jacuzzi / Sundance hot tub: flow switch problem

The flow switch is not reading correctly, so the heater is off. A flashing FLO usually means no flow with the pump on. A solid FLO usually means the switch is stuck closed with the pump off.

Also shown as: FLOW, flashing FLO, solid FLO

Most likely causes

  1. 1Dirty or clogged filtermost likely
  2. 2Low water level or an air lockcommon
  3. 3Failed flow switchcommon
  4. 4Failed circulation pumpless common

What to try, in order

  1. Check the water level.
  2. Turn off power at the breaker, remove the filter, and rinse it.
  3. Restore power and run the tub briefly with the filter out. If the code clears, deep clean or replace the filter.
  4. Bleed air after a refill by pulsing the jets pump.
  5. If the code stays with good flow, the flow switch is the likely part.

FLO questions

Can I use my Jacuzzi with FLO on the display?

Yes, but it will not heat until the flow problem is fixed.

What is the most common fix?

A clean or new filter. After that, the flow switch itself is the usual culprit.

Related codes

Balboa FLO · Low water flowGecko FLO · No water flow detectedHydro-Quip FLO · Flow or pressure switchJacuzzi / Sundance -- · Watchdog shutdownJacuzzi / Sundance COOL · Water 20°F below setJacuzzi / Sundance FL1 · No flow detectedJacuzzi / Sundance FL2 · Flow switch stuck closedJacuzzi / Sundance HOLD · Panel buttons locked out

General guidance. Follow your manufacturer's instructions; anything inside the control box is work for a licensed professional. Updated October 5, 2026.