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

Temperature sensor failure. The temperature sensor (thermistor) input failed.

Can I fix Hayward code SF myself?

Start with these safe checks: Note the code and call a qualified tech. Sensor replacement is inside the heater cabinet.

When should I call a technician for code SF?

Sensor replacement is inside the heater cabinet. 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 SF: Temperature sensor failure

What SF means

The temperature sensor (thermistor) input failed.

Likely causes

Sensor or wiring fault

Safe first checks

Note the code and call a qualified tech.

When to stop

Sensor replacement is inside the heater cabinet.

Parts that may help

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

Sundance/Jacuzzi 3-Pin Temperature Sensor, 12 ft Cable – 6600-751$59.99

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.