FLO / FL / FLC — Flow Error
Flow errors are the most common error code in Tri-Cities spas. The flow sensor detects insufficient water movement through the heater — which triggers this code and prevents heater operation to avoid element burnout from running dry.
Most common causes in the Tri-Cities:
- Dirty filter: The first thing to check. A clogged filter restricts flow below the sensor's minimum threshold. Remove the filter and run the spa briefly without it — if the FLO error clears, filter replacement or cleaning is the fix.
- Calcium-blocked flow sensor: The flow sensor itself can become coated with scale, making it less sensitive and causing false FLO errors even when flow is adequate. Scale on the sensor flag or paddle impairs its ability to detect water movement accurately.
- Closed or partially closed valve: A gate valve or diverter valve in the partially closed position restricts flow enough to trigger the sensor.
- Air lock after refill: Air trapped in plumbing prevents flow sensor activation.
OH / OHH — Overheat Error
The OH error means water temperature has exceeded the high-limit threshold (typically 108–112°F depending on system). In the Tri-Cities, this is a summer-specific issue — a spa sitting in direct afternoon sun with a dark cover can absorb enough solar heat to push water temperature past the high-limit without the heater ever running. This is the protection system working correctly.
Let the spa cool with the cover off. Once water temperature drops below the reset threshold (usually 95°F), the system should clear the error automatically and resume normal operation. If the OH error occurs repeatedly without obvious solar heating as the cause, the temperature sensor or high-limit sensor may be reading inaccurately.
HH — Heater High Limit
HH (or HL on some systems) indicates the high-limit sensor has tripped at the heater element — different from the OH code which reflects water temperature. The high-limit sensor monitors element surface temperature, which can spike even when water temperature is normal if flow past the element is reduced. In the Tri-Cities, calcium scale on the element surface creates hot spots that trip the high-limit even with adequate water flow. Regular descaling extends the interval between HH trips.
DRY / DR — Dry Heater
The DRY error means the heater sensors are not detecting water around the element — the heater is running or attempted to run without water contact, which would burn it out. Reset by restoring proper water level and flow. If the spa has adequate water level and the DRY error persists, the pressure switch or flow sensor has failed and is not correctly reporting water presence to the control board.
SN / SNS — Sensor Error
Sensor errors indicate the control board cannot read one of its temperature sensors accurately. Sensors fail from heat exposure and calcium contamination on the sensing element. A spa that shows wildly inaccurate water temperature readings before showing an SN error likely has a sensor coated with scale or a sensor whose wiring has degraded from heat exposure in the equipment bay.
Service in the Tri-Cities
Desert Spa Repair diagnoses control system and error code issues across Kennewick, Richland, Pasco, West Richland, Benton City, and Finley. We carry common sensors, flow switches, and control boards for Balboa and Gecko systems. Fixed quote after diagnosis, same-day available most days.