Hot Tub Error Codes Explained (FLO, HL, OH, DR & More)

Hot tub error codes are designed to protect your spa from damage and unsafe operating conditions. While the exact wording or display may vary by brand and control system, most error codes point to problems with water flow, heating, temperature sensors, or system modes.

This guide explains the most common hot tub error codes, what they usually mean, what causes them, and what you can safely check before calling a professional. Where available, each code links to a detailed step-by-step troubleshooting guide.

I have found that Most error codes are caused by the same underlying problems.
See: Hot Tub Flow Issues and High limit issues

How to Use This Hot Tub Error Code Guide

Identify the error code shown on your spa control panel
Find the matching code below
Click the code name for detailed troubleshooting
Always perform basic checks before replacing parts

⚠️ Safety First: Hot tubs combine electricity, water, and heat. If you are unsure or uncomfortable performing any step, stop and contact a qualified spa technician.

Before Troubleshooting Any Hot Tub Error Code

Start here — these steps resolve a surprising number of error codes:

Verify the water level is above all jets
Remove and clean the filter, then test again
Confirm all slice valves are fully open
Bleed air from the pump if the spa was recently drained
Power-cycle the spa after correcting any issues

Universal / Generic Hot Tub Error Codes

(Found on many brands and control systems)

FLO / FL / FL1 – Flow Error

Indicates insufficient water flow through the heater.
Common causes include dirty filters, closed valves, air locks, circulation pump issues, or a failing flow switch.

FLC / FL2 – Flow Switch Stuck Closed

The system detects flow when there should be none.
Often caused by a stuck or faulty pressure/flow switch or wiring issues.

OH / OHH – Overheat Error

Water temperature has exceeded safe operating limits.
Usually triggered by restricted flow, dirty filters, failed sensors, or heater issues.

SN / SN1 / SN2 – Temperature Sensor Error

The control system is receiving incorrect or missing data from temperature or high-limit sensors.
This may be caused by a failed sensor, loose connection, or damaged wiring.

HL / HLoH – High-Limit Error

The safety high-limit sensor has tripped to prevent overheating.
Often related to flow problems or sensor failure.

DR / DRY – Dry Heater Error

The heater is operating without sufficient water flow.
Usually caused by low water level, air in the plumbing, or circulation pump failure.

COL / COOL – Water Too Cool

The spa water temperature has dropped significantly below the set point.
This may occur during cold weather or extended inactivity.

LOC / L1 / L2 – Control Panel Locked

The spa’s control panel has been locked to prevent accidental changes.
This is typically user-activated and not a system fault.

EC / ECON / ECO – Economy Mode

The spa is operating in energy-saving mode and will only heat during programmed cycles.
This is normal behavior, not a malfunction.

SLP / SLPY – Sleep Mode

A deeper energy-saving mode that allows the water temperature to drop further than Economy mode.

ICE / IC – Freeze Protection Active

The spa has detected near-freezing temperatures and is circulating water to prevent damage.
This is normal protective operation.

PF / PR / PRR – Priming Mode

The spa is in startup or priming mode, usually after power loss or refilling.
This is normal and should clear automatically.

Balboa Control System Error Codes

Balboa systems are commonly used across many spa brands.

A more complete list of Balboa error codes can be found here: Balboa Error Codes Explained

— — — – Heater off, system idle
dy – Heater dry (no water detected)
drY – Heater dry for extended time
OH – Overheat condition
Sn1 / Sn2 – Temperature or high-limit sensor fault
PR / PRR – Priming mode active
LOC / LOP – Control panel lockout

Gecko Control System Error Codes

Common on many mid- to high-end spas.

FLO – Flow problem detected
FLC – Pressure switch fault
HR / HL – High-limit error
PR – Priming mode
Sn / Snb / Snt – Sensor issues
OH / OHH – Overheat
COOL – Water temperature dropped
ICE – Freeze protection active

Watkins / Hot Spring Spa Error Indicators

These systems often use icons or lights instead of traditional codes.

FLO – Flow issue
DR – Dry heater
OH – Overheat
SNS – Sensor fault
IC – Freeze protection active
— — – Normal idle / ready mode

Indicator Lights:

Flashing red/green: Flow issue
Flashing blue: High-limit issue
Flashing yellow: Salt system issue or salt cell needs cleaning

Caldera, Sundance, and Jacuzzi Spa Error Codes

FL1 / FL2 – Flow switch errors
OH / OHH – Overheat
Sn1 / Sn2 – Sensor issues
COL – Cooling mode
HL – High-limit error
DR / DY – Dry heater
EC / ECO / SLP – Economy or sleep mode
ICE – Freeze protection active

When to Call a Professional

Call a qualified spa technician if:

Error codes return immediately after basic checks
The breaker trips repeatedly
You smell burning or see damaged wiring
The heater or control board appears faulty

Still Not Sure What’s Wrong?

If you’ve gone through the steps in this guide and you’re still unsure what to do next, I offer personalized email consultations.

I’ll review your symptoms, photos (if needed), and the information you’ve gathered to help you determine the most likely cause and the best next step—whether that’s a simple DIY fix or calling a professional.

👉 Learn more about my Pool & Spa Consultation Service

Hot Tub Error Codes – Meanings, Causes, and Troubleshooting