Cal Spas error codes for Balboa and Gecko models

Short answer

Cal Spas publishes separate 2026 manuals for its Balboa- and Gecko-equipped models, so first check which you have. On Balboa models, code 27 (MO27) means the heater is dry, 28 that it may be dry, 17 that heater flow failed and 30 that the heater reached 118°F. On Gecko models, FLO, HL and OH mean what they mean on any Gecko pack.

Updated October 2026By the HotTubFinder research desk

A hot tub control panel showing an error code, and the owner's manual, which names the control system — The panel shows the code. Its label is often the spa's brand, so check the manual for the control system.

What you can check yourself

Check the water level and top it up to the line in your manual.
Clean the filter, or replace it if it is worn.
Open any closed valves and jets.
Purge an air lock the way your owner's manual describes.
Clear the message on the panel once the cause is fixed.

Where the owner's part ends

Anything else: turn off power at the breaker and call a technician.

Heaters, pumps, sensors and the control board sit on mains power next to water. Never bypass a sensor, a pressure or flow switch, or a high-limit to get a tub running: they are what stop it from overheating.

Does my Cal Spa use Balboa or Gecko codes?

Either, depending on the model. Cal Spas publishes its 2026 Patio and Patio Plus manual twice, once for Balboa equipment and once for Gecko, and its Platinum manual prints Gecko's error list. The Balboa manual prints the numbers as MO27, MO28 and so on; Balboa's own guide writes them M027 and M028.

Balboa message codes in Cal Spas' 2026 Balboa manual (MO15 to MO44)

15 codes

Balboa message codes in Cal Spas' 2026 Balboa manual (MO15 to MO44)
Code	What it means	What to do
M015	Panel: Sensors are out of syncThe two temperature sensors in the heater may disagree by 2 to 3°F. Balboa says to call for service.	Technician Call for service if it does not clear within a few minutes.
M016Also: HFL	Panel: The water flow is lowNot enough water is moving through the heater to carry the heat away. The heater waits about a minute and tries again.	Check first Check the water level and top it up to the line in your manual. Clean the filter, or replace it if it is worn. Open any closed valves and jets. Purge an air lock the way your owner's manual describes. Call if it keeps coming back after the checks.
M017Also: LF	Panel: The water flow has failedFlow through the heater stayed too low and the heater has been switched off. It stays off until you clear the message.	Check first Check the water level and top it up to the line in your manual. Clean the filter, or replace it if it is worn. Open any closed valves and jets. Purge an air lock the way your owner's manual describes. Clear the message on the panel once the cause is fixed. Call if it returns after the checks and one reset.
M019	Panel: Priming modeNormal at every power-up. For 4 minutes you can run each pump to push air out; the heater stays off until priming mode ends.	Normal Nothing to do: this is the spa working as designed.
M026	Panel: Sensors are out of sync, call for serviceThe heater's two sensors have disagreed for at least an hour.	Technician Call for service.
M027	Panel: The heater is dryThere is not enough water in the heater to start it, so the spa is shut down until the message is cleared.	Check first Check the water level and top it up to the line in your manual. Clean the filter, or replace it if it is worn. Open any closed valves and jets. Purge an air lock the way your owner's manual describes. Clear the message on the panel once the cause is fixed. Call if it comes back after the checks.
M028Also: dr	Panel: The heater may be dryThe heater may be dry or short of water. The spa shuts down for 15 minutes, then tries again.	Check first Check the water level and top it up to the line in your manual. Clean the filter, or replace it if it is worn. Open any closed valves and jets. Purge an air lock the way your owner's manual describes. Call if it repeats after the checks.
M029Also: OHS	Panel: The water is too hotA sensor read 110°F (43.3°C) in the spa water and spa functions stop. It resets on its own below 108°F (42.2°C). Long pump runs or hot weather can cause it.	Stay out Stay out of the water. Take the cover off so the water can cool. Call if it does not reset once the water cools, or keeps happening.
M030Also: OHH	Panel: The heater is too hotA sensor read 118°F (47.8°C) inside the heater and the spa shut down. It can be cleared only once the water is below 108°F (42.2°C).	Stay out Stay out of the water. Take the cover off so the water can cool. Clean the filter, or replace it if it is worn. Check the water level and top it up to the line in your manual. Open any closed valves and jets. Call if it happens again after one reset.
M031	Panel: Sensor A faultTemperature sensor A or its circuit has failed.	Technician Call for service.
M032	Panel: Sensor B faultTemperature sensor B or its circuit has failed.	Technician Call for service.
M034	Panel: A pump may be stuck onA pump appears to be stuck running, and the water may be overheating.	Stay out Stay out of the water. Power down the spa and call for service.
M035	Panel: Hot faultA pump appears to have been stuck on when the spa was last powered.	Stay out Stay out of the water. Power down the spa and call for service.
M036	Panel: The GFCI test failedNorth America only. The system could not test or trip the GFCI, which may mean an unsafe installation.	Technician Contact your dealer or service company.
M044	Panel: J29 warningJ29 is a heater-disable input on the control board. The message shows if it is shorted at power-up.	Technician Contact your dealer if it appears after several power-ups.

Meanings are from Balboa's own guide; Cal Spas' manual prints the same list. All Balboa codes: Balboa error codes.

What should I check for code 16, 17, 27 or 28?

All four are about water reaching the heater. The Cal Spas Balboa manual lists the same flow checks for each: low water level, suction restrictions, closed valves, trapped air, too many closed jets and pump prime. The ones marked with a star in the manual (17, 27, 28 and 30 among them) clear with any button press once the cause is fixed.

Gecko messages in Cal Spas' 2026 Gecko and Platinum manuals (selected)

8 codes

Gecko messages in Cal Spas' 2026 Gecko and Platinum manuals (selected)
Code	What it means	What to do
HL	Panel: High Limit circuit has trippedThe heater's high-limit safety circuit has tripped.	Stay out Stay out of the water. Take the cover off so the water can cool. Clean the filter, or replace it if it is worn. Call if it trips again.
FLOAlso: FLO - L01, FLO - L02	Panel: FLO conditionA no-flow condition. Gecko's own list says to check the filter, pump, blockage, air lock and water level.	Check first Clean the filter, or replace it if it is worn. Check the water level and top it up to the line in your manual. Open any closed valves and jets. Purge an air lock the way your owner's manual describes. Call if it persists.
NO FLO	Panel: Persistent NO FLO, all offThe no-flow condition persisted and everything has been shut off.	Check first Clean the filter, or replace it if it is worn. Check the water level and top it up to the line in your manual. Open any closed valves and jets. Purge an air lock the way your owner's manual describes. Call if it returns after the checks.
OH	Panel: Spa temperature is too highThe spa water is too hot.	Stay out Stay out of the water. Take the cover off so the water can cool. Call if it returns once the water cools.
Pr	Panel: Temp probes or detection circuit are defectiveOn this keypad, Pr is a probe fault, not priming.	Technician Call for service.
AOH	Panel: Elevated internal temperatureThe control's internal temperature is high.	Technician Call if it persists.
Hr	Panel: Hardware error was detected (thermal fuse)A thermal fuse fault.	Technician Call for service.
UPL	Panel: The spa pack does not have valid softwareNo valid software on the pack.	Technician A technician reprograms it.

All Gecko messages: Gecko error codes.

What does FLO mean on a Gecko-equipped Cal Spa?

The pack sees no water flow while the pump runs. Cal Spas' Gecko manual lists two FLO messages: a no-flow condition, and no flow for more than 2 hours. The checks are the same as on any tub: filter, water level, valves and air. See FLO and flow errors.

Common questions

What is Cal Spas error code 27?

On Balboa-equipped Cal Spas, MO27 means the heater is dry: not enough water in it to start, so the spa shuts down. Fix the water level, filter, valves or air lock, then press any button to clear it.

What is Cal Spas error code 30?

MO30 means the heater is too hot: a sensor read 118°F (47.8°C) in the heater and the spa shut down. Stay out of the water and clear it once the water is below 108°F. If it returns, call for service.

What is Cal Spas error code 17?

MO17 means the water flow through the heater has failed and the heater is off. Check the water level, suction, valves, trapped air and pump prime, then clear it with a button press.

How do I know if my Cal Spa has Balboa or Gecko controls?

Cal Spas prints separate 2026 owner's manuals for Balboa and Gecko equipment, and its Platinum manual uses the Gecko list. The title of the manual that came with your tub tells you which list applies, and your dealer can confirm it.

Sources

Balboa TP400/TP600 user guide (40940_N), panel messages balboawater.com · checked October 2026
Cal Spas Patio and Patio Plus owner's manual, Balboa equipment, 2026 calspas.com · checked October 2026
Gecko in.k1000 techbook, error messages geckoalliance.com · checked October 2026
Cal Spas Patio and Patio Plus owner's manual, Gecko equipment, 2026 calspas.com · checked October 2026
Cal Spas Platinum owner's manual, 2026 calspas.com · checked October 2026

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