Modern hot tubs display error codes on the control panel when something goes wrong. This guide covers the most common codes across Balboa, Gecko, and Spa Touch control systems — but always check your specific manual, as codes can vary by manufacturer.
First step for any error code: Power cycle the tub — switch it off at the isolator, wait 30 seconds, switch back on. This clears many temporary faults. If the code returns, investigate further.
FLO / FL / Flow Error
What it means: The control system has detected insufficient water flow through the heater. This is a safety feature — the heater won't run without adequate flow to prevent it burning out.
Common causes:
- Blocked or dirty filter — the most common cause by far
- Air lock in the pump after a refill
- Low water level (check the water is above the skimmer line)
- Closed or partially closed valves
- Failing circulation pump
- Faulty flow switch or pressure switch
Try first: Clean or replace your filter. Check water level. If you've recently refilled, run the jets for a few minutes to purge any airlocks.
Call us if: The code persists after a clean filter and power cycle — the pump or flow switch may need inspection.
Rather have an engineer look at it? We service and repair hot tubs across Lincolnshire, from Grimsby and Lincoln to Grantham and Doncaster.
Book a visit01472 400673OH / OHH / High Limit
What it means: The water or heater temperature has exceeded the safe limit (usually 43°C). The heater has shut off as a safety measure.
Common causes:
- Hot weather — direct sunlight on the tub cover can raise water temperature
- Cover left off in summer
- Thermostat set too high
- Faulty temperature sensor or high-limit sensor
- Failing topside control
Try first: Remove the cover, let the water cool, power cycle. If it's a hot day, this is likely the cause.
Call us if: The error appears in cold weather or when the water temperature is clearly within normal range — this suggests a sensor fault.
DR / DRY / Dry Fire
What it means: The heater has attempted to run without detecting water. This is a critical safety fault — the heater will have shut down to prevent damage.
Common causes:
- Very low water level
- Air lock — common after refilling
- Failed circulation pump
Try first: Check water level. If you've recently refilled, purge airlocks by briefly loosening a union fitting. Power cycle.
Call us if: The water level is correct and the error persists — this needs a professional diagnosis.
CD / Cold / Freeze Protection
What it means: The water temperature has dropped to a level where freeze protection has activated. The pump will run continuously to prevent the pipes freezing.
What to do: This is a safety mode, not necessarily a fault. Check the tub is powered and the set temperature is correct. In very cold weather this is normal. Do not switch the tub off — you risk freezing the pipework.
SL / Sleep Mode
What it means: The tub is in economy or sleep mode and only heating to 20°C below the set temperature. Not a fault — adjust your timer settings if you want it ready at a specific time.
Err / Error (generic)
What it means: A general fault has been detected. On some systems, pressing the "Jets" or "Light" button will display a more specific code.
Blinking temperature display
On many Balboa systems, a flashing temperature reading indicates the water hasn't yet reached the set temperature. This is normal — particularly after a water change or in cold weather.
When to call a professional
You should call us if:
- The error code returns immediately after a power cycle
- You've checked the obvious causes and can't identify the problem
- The error relates to a heating or electrical fault
- The tub is losing water (a leak)
- You're not confident working around electrical components
We diagnose and fix all these faults. Book a diagnosis or call us on 01472 400673 and we'll talk you through it first.