Display shows FLO2 and spa may shut down heater and pumps; often occurs when jets pump is running.

Safety first: Turn off power at the GFCI breaker before working in the equipment bay.

• 1. Power cycle the spa: Turn the breaker OFF for 30 seconds, then ON. Observe if FLO2 returns immediately or only when pumps run.
• 2. Inspect flow switch wiring: Locate the flow switch on the heater plumbing. Check that the two-wire harness is not pinched, cut, or corroded at the connector on the Sundance control board.
• 3. Check for stuck switch: With power OFF, gently tap the body of the flow switch with the handle of a screwdriver to free a stuck paddle or plunger. Do not hit hard or disassemble the switch.
• 4. Verify plumbing orientation: Ensure the arrow on the flow switch body matches the direction of water flow through the heater tube. Incorrect installation can cause FLO2.
• 5. Advanced test (for technicians): With power OFF, disconnect the flow switch from the board and measure continuity across the switch terminals with a multimeter. It should be open (no continuity) when there is no flow. If it reads closed, the switch is defective.
• When to call a technician: If the switch tests good but FLO2 persists, the control board input may be faulty and should be diagnosed and replaced by a professional.