Hot Tub Error Codes: What They Mean and When to Worry

Error codes are your hot tub's way of telling you something is wrong. The good news is that many of them are minor issues you can fix yourself. The bad news is that every manufacturer uses different codes. Here are the most common ones we see across the brands popular in Utah (Jacuzzi, Hot Spring, Sundance, Bullfrog, and Master Spas).

FLO / FL / FLC: Flow Error

This is the #1 error code we get called about. It means the system isn't detecting enough water flow through the heater. The heater shuts off to prevent damage (heating without flow = burnt element).

Common causes: dirty filter (clean or replace it first, since this fixes it 80% of the time), closed valve, air lock after a refill, or a failing pressure switch. Start by cleaning the filter. If that doesn't fix it, check that all valves are open. If you just refilled, you may have an air lock: shut off power at the breaker first, then open the bleed valve near the pump or loosen the pump union slightly to let air escape. Never loosen a union with the power still on.

OH / OHH: Overheat

The water temperature has exceeded the safe limit (usually 108-110°F). The system shuts everything down to prevent scalding. This can happen if the temperature sensor is faulty, if there's a flow problem causing the heater to overheat a small pocket of water, or on very rare occasions, a stuck relay keeping the heater on.

Fix: Remove the cover to let heat escape. Don't get in. Once it cools below 104°F, the system should reset. If it happens repeatedly, call a pro: repeated overheating usually indicates a sensor or relay problem.

SN / SNS: Sensor Error

A temperature sensor is reading out of range or out of balance with its partner sensor. If the code alternates with a normal temperature reading, it can be a temporary condition, so let it run a cycle before worrying. If it persists, that's a service call. On Balboa systems, a dedicated SA or SB code points at one specific sensor that's actually failed and does mean replacement; the part is usually $20-50, but accessing it can be labor-intensive depending on the model.

ICE / IC: Freeze Protection (not a fault)

This one is easy to mistake for a problem, but it isn't one: ICE means your tub detected near-freezing water and automatically started running the pump to keep the plumbing moving so nothing freezes and cracks. No action needed on your end. Don't unplug the spa or cut power, since that's exactly what stops the protection from working. Leave the cover on as normal; it runs regardless. On Gecko-based systems this can show as ICE or as "Smart Winter Mode" (SWM) depending on your control system, but the meaning is the same. The one time to actually call someone: if you see this code when it genuinely isn't cold out, since that can point to a sensor giving a false reading rather than a real freeze risk.

DR / DRY: Dry Fire Protection

The heater detected insufficient water contact and shut down to prevent element damage. This often happens when the water level is too low. Check your water level: it should be above all the jets. Top off if needed. If the water level is fine, you likely have a flow issue (see FLO above).

COOL / COL: Temperature Falling

The water is more than 20°F below the set temperature. In Utah winters, this can trigger after a power outage or if the heater can't keep up with extreme cold. Check that the heater is running and the cover is in good shape. If the heater is on but the water isn't warming, the heating element may need replacement.

When to DIY vs. Call a Pro

• DIY: Filter cleaning, topping off water level, checking valves, clearing air locks, removing cover to cool an overheated tub
• Call a pro: Repeated error codes after basic fixes, sensor errors, relay problems, heater not heating, any error combined with unusual noises or burning smell