Hayward Pool Heater IF / IO Error Code

Updated 2026-08-29 · review status: manual-verified Last verified: 2026-08-29

Quick answer

Ignition Failure Ignition failure during startup sequence. Heater clicks, blower runs, but never lights. No gas supply or gas pressure too low, weak or failed igniter, dirty or failed flame sensor, air in gas line after service. Check that manual gas valve is open and other gas appliances work. Inspect igniter for cracks (should glow bright orange). Clean flame sensor with fine sandpaper. If gas w

Severity: high · DIY difficulty: intermediate

Safety

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What IF / IO means

Ignition Failure Ignition failure during startup sequence. Heater clicks, blower runs, but never lights. No gas supply or gas pressure too low, weak or failed igniter, dirty or failed flame sensor, air in gas line after service. Check that manual gas valve is open and other gas appliances work. Inspect igniter for cracks (should glow bright orange). Clean flame sensor with fine sandpaper. If gas was recently off, may need several ignition attempts to purge air.

Causes, ranked

  1. 1. IF: maximum ignition retries exceeded - gas supply off/low, poor ignition common diy-ok

    Check:

    Fix:

  2. 2. IF: failed igniter or gas valve occasional pro-only

    Check:

    Fix:

  3. 3. IO: igniter circuit open while blower runs - failed igniter or wiring occasional pro-only

    Check:

    Fix:

Parts & supplies for Hayward Pool Heater: filters, control boards, sensors, and common replacement parts.

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Commonly searched as: "hayward if / io" · "hayward error code if / io" · "hayward air conditioner if / io"

Sources

  • PoolDial error-code reference (manual-backed) — verified 2026-08-29
  • Hayward H-Series H150FD-H500FD Service & Installation Manual (Figure 27: Error codes) — verified 2026-08-29
  • PoolDial error-code reference (manual-backed) — verified 2026-08-29