What does error code IO mean on a Hayward pool heater?

Ignitor circuit open. The ignitor circuit is open.

Can I fix Hayward code IO myself?

Start with these safe checks: Note the code and call a qualified tech. Ignitor replacement is gas-appliance work.

When should I call a technician for code IO?

Ignitor replacement is gas-appliance work. Smell gas? Leave right away, don't touch light switches or phones inside, and call your gas utility or 911 from outside. Never open a gas valve, burner, gas line, vent or flue connection, or bypass a safety switch. Repeated lockouts, scorching, soot, or a CO alarm mean shut it off and call a licensed gas technician.

Hayward Pool Heater Error Code IO: Ignitor circuit open

What IO means

The ignitor circuit is open.

Likely causes

Failed ignitor or wiring

Safe first checks

Note the code and call a qualified tech.

When to stop

Ignitor replacement is gas-appliance work.

Parts that may help

Only order a part once the checks above point to it, and match the part number to your model.

Jandy Igniter Assembly Hi-E2 (R0457503)$100.99

Checked against: Hayward Universal H-Series heater troubleshooting guide (UHS16b): diagnostic codes. Codes can differ by model and year, so confirm with your owner's manual.