The most likely fix on a Raypak fault code: power-cycle the breaker once, then look at gas. In our field experience, the big four fault families — IF (Ignition Failure), IGN (ignition sequence), OS1 (outlet sensor), and ILO(Ignition Lockout) — resolve to gas-supply or sensor issues a large share of the time. Resetting the same fault three times in a row without checking gas pressure is how heaters get sent for parts they don't need. Note that exact code labels and reset sequences vary across the Raypak digital-display lines (106A, 206A, R-series, Avia, Versa) — always verify against the service manual that shipped with your unit.
Most common symptoms
- Display shows two- or three-letter code; heater will not fire.
- Heater attempts to light, fails, retries twice, then locks out.
- Heater fires briefly then drops out, sometimes with a soft thud.
- Display reads OS1 with the heater otherwise looking fine.
- Heater works in cool weather but locks out under load on hot days.
Field-fix list by code
- IF — Ignition Failure. Three attempts, no flame proven. Check gas valve open, igniter clean, flame rod free of corrosion, condensate cleared, and inlet gas pressure under full fire.
- IGN — Ignition sequence. Not a fault. The heater is in the purge/light cycle.
- ILO — Ignition Lockout. The heater has stopped trying. Reset, then diagnose. ILO repeating after one reset = real combustion issue.
- OS1 — Outlet Sensor. Sensor or wire fault. Replace the sensor; check the harness for damage.
- AFS — Air Flow Switch. Pressure switch on the combustion blower didn't close. Vent obstruction (a bird's nest or a stuck damper), failed blower, or a clogged pressure-tap tube.
- HLS — High Limit Switch. The heat exchanger got too hot. Restricted flow, scaled exchanger, or an actual sensor fault. Check water flow and exchanger condition before suspecting the switch.
Diagnostic walkthrough
- Photograph the code. Some Raypaks blink the code; the photo prevents a misread.
- Gas first. Verify the supply at the meter. Try a kitchen burner — gas at the house? Then the fault is downstream at the heater regulator or line.
- Flow second. Pump running, valves open, filter pressure within range. Most HLS faults clear when flow comes back.
- Power-cycle once. Breaker off 30 seconds, on again. One reset attempt; if the same code returns within seconds of relight, stop and diagnose.
- Open the cabinet (pro work). Cabinet inspection for spider webs in the venturi (a Florida specialty), condensate puddles in the burner tray, corroded flame rod, and dirty igniter is licensed-tech work — gas off, breaker locked out, manometer in hand.
- Manometer test. The definitive call on IF/ILO. Gas pressure under full fire must hold to spec. Sag = supply problem.
Step-by-step fix
Clean the igniter and flame rod with fine emery cloth. Clear the burner tray of condensate and debris. Replace a failed sensor (OS1) with the matching part number. Manometer the gas; if it sags under load, the line is undersized or the regulator is failing — that is plumber/gas-fitter work. See our gas heater line sizing guide for what the supply should look like.
South Florida-specific failure modes
- Spider webs in the venturi. Florida outdoor heaters get spiders in the gas-air mixing tube. The webs choke combustion, you get IF or ILO every spring. Annual venturi cleaning prevents this.
- Condensate pooling in coastal cabinets. Cool nights + warm cabinets = condensation on the burner tray. Salt-laden condensate corrodes the flame rod. Inspect twice a year.
- Salt-air corrosion of low-voltage harness. The OS1 sensor harness rots at the connector within 5–7 years on coastal pads. Dielectric grease the connectors at install.
- Lightning damage to the ignition control board. Florida summer storms take out IFC boards faster than the burner ever fails.
When it's time to replace
A Raypak heat exchanger that has failed (water through the burner) is end-of-life. A 12+ year heater with a failed control board, a corroded burner, and a leaking exchanger is replace, not repair. See our pool heaters comparison for what comes next — gas, heat pump, or solar.
When to call a pro
Manometer testing, regulator work, and burner-tray inspection are licensed-tech jobs. A heater is gas, fire, and water in one cabinet — not the place to learn. In Florida, pool heater repair work is regulated by the DBPR (RP / CPC license categories), and gas-side work also requires a licensed gas-fitter. Schedule a pool equipment repair visit and we will diagnose with a flat-rate quote.
FAQ
What does IF mean?Ignition Failure — gas, igniter, flame rod, or pressure.
What does OS1 mean?Outlet sensor open or shorted — replace.
What does ILO mean?Ignition Lockout — the heater has stopped retrying. Reset once, then diagnose.
What does AFS mean?Air-Flow Switch fault — vent or blower obstruction.
Are codes the same across all Raypaks?[VERIFY] Mostly yes on the digital-display models, but always confirm against the unit's service manual.
Want a pro to handle this?
Our CPO-certified techs run this exact playbook on every weekly service visit.