Hot tub error codes
Quick answer
Most hot tub codes fall into a few families: flow (often FLO, FL, or FLC), overheat (OH, HH, or HOT), sensor (Sn and its variants), and dry or low water (dr or dY). They are safety messages, and the pack cuts the heater to protect the tub. Exact letters vary by controller, so your panel manual is the authority, but the families below cover the common Balboa and Gecko packs and what to do about each.
A code is the tub telling you why it stopped heating, not a random fault. Identify which family yours belongs to, and the fix is usually the same checks you would run anyway: flow, water level, and the filter.
The common code families
| Family | Often shown as | What it means | First fix |
|---|---|---|---|
| Flow | FLO, FL, FLC, FLO1 | The pack cannot confirm water is flowing through the heater | Clean the filter, top up water, clear an air lock, check the circulation pump |
| Overheat | OH, HH, OHH, HOT | The water or heater is above the safe temperature | Power off, lift the cover, let it cool, then check flow |
| Sensor | Sn, SnA, SnB, SE | A temperature sensor reads open, shorted, or mismatched | A sensor fault is a technician job; power-cycle once first |
| Dry / low water | dr, dY, dRY | The heater senses little or no water around it | Top up water, clear an air lock, restore flow |
| Freeze / cool | ICE, CO, COOL | Freeze protection or a cool-water notice, usually informational | No action; the tub is protecting itself or still warming |
| Communication | COM, PnL, comms | The topside panel and the pack are not talking | Check the panel cable and connections; often a technician job |
Letters and exact wording differ between Balboa, Gecko, and other packs, and between board versions, so always confirm against your own controller's manual.
What to do when a code shows
- Note the exact code as shown, including any number after it.
- Run the flow checks. Most codes trace back to flow, so clean the filter, top up the water, and clear an air lock. See not heating and jets not working.
- Power-cycle once at the breaker after restoring flow, which clears a latched flow or overheat state.
- Look it up in your controller manual. Identify the pack brand (Balboa, Gecko or Aeware, HydroQuip, and so on) and read that maker's topside panel manual for the exact code, which is the authoritative source.
- Call a technician for sensor, element, or communication faults, which need parts and testing.
Switch off at the breaker before opening the equipment bay, since the pack carries mains voltage next to water. Leave sensor, element, and board repairs to a qualified spa technician.
What helps
Since flow codes are the most common and a clogged cartridge is the usual cause, a clean or spare filter clears more codes than any other single thing.
Get replacement spa filter cartridge Get filter cleaner
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Common questions
What does FLO or FLC mean on a hot tub?
It is a flow message: the pack cannot confirm water is moving through the heater, so it stops heating to stay safe. The usual causes are a dirty filter, low water, an air lock after a refill, or a weak circulation pump. Clear the flow problem and the code clears.
How do I reset a hot tub error code?
First fix the underlying cause, usually flow, then power the tub off at the breaker for a minute and back on to clear a latched code. If the code returns immediately, the fault is still present; do not just keep resetting it.
Do all hot tubs use the same codes?
No. The families are similar across packs, but the exact letters and numbers differ between Balboa, Gecko, and other controllers and between board versions. Use the families here to understand the type of fault, then confirm the precise meaning in your own controller manual.