Reference, applied
The Index in Use
FLO, OH, dr, Sn and friends — what the pack is trying to tell you, and which messages are safe to handle yourself.
Every spa pack speaks a compact dialect of two-to-four-character complaints. Some are precise, some are the machine guessing, and a couple mean 'stop resetting me and call someone'. This index covers the codes we see weekly across Balboa and Gecko systems in the Tri-Cities — photograph yours before any reset, and bring it to the call: the diagnosis starts before the van does.
| Code | What it means | Usual suspects | Your move |
|---|---|---|---|
| FLO / FL1 / FL2 | Flow fault — the heater is not seeing enough water | Dirty filter, air lock after a refill, weak pump, stuck pressure switch | Pull the filter and retry; if the code stays, book the pump side |
| OH / OHH / HH | Overheat — water above the safe ceiling | Summer sun-load under a closed cover, failing probe, restricted flow | Open the cover, cool it down; recurring trips need a probe test |
| dr / dY / dr9 | Dry — the heater thinks there is no water at all | Low water level, big air lock, failed sensor | Top up above the skimmer, bleed the pump; then call if it persists |
| Sn / Sn1 / Sn3 | Sensor circuit open or shorted | Failed temperature or high-limit probe, damaged input on the board | No DIY here — the probe and the board input need measuring |
| HL / HLoH | High-limit tripped | Genuine overheat, scale-insulated element, drifting limit switch | Reset once; a second trip is a service call, not a coincidence |
| LF | Persistent low flow — repeated FLO lockout | Same causes as FLO, further along | The pack has given up retrying; the flow path needs real attention |
| PSoC / PSoL | Pressure switch fault | Switch stuck open or closed, often mineral | Serviceable — and a common misdiagnosis as a 'bad heater' |
| ---- / blank | Display dead or dashes | Ribbon cable, topside panel, or pack power supply | Breaker off and on once; if it returns blank, the cable gets tested first |
Brand-specific packs add their own vocabulary — Gecko's in.xe series flags low voltage that long rural feeds cause, Hot Spring's IQ boards blink patterns instead of letters. If your code is not on this table, it is probably still in our notebook.
Real faults, real fixes — the paperwork version, minus the addresses.
Ribbon cable green with corrosion at the pack plug. Cleaned, sealed, panel lived.
Water at 106° and climbing. Board-level relay swap on a BP501 — pack saved.
Read it to us over the phone — half the time we can tell you the likely part before the visit.