Can I fix A.O. Smith code 8 flashes myself?

Start with these safe checks: Turn the knob to OFF and look through the viewport. If there's no pilot flame, wait 10 minutes and relight following the label. If a pilot flame is still there with the knob OFF, turn the main gas supply off and call a qualified technician; the gas control needs replacing.

When should I call a technician for code 8 flashes?

If a pilot flame is still there with the knob OFF, turn the main gas supply off and call a qualified technician; the gas control needs replacing. 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.

A.O. Smith Water Heater Error Code 8 flashes: Power off failure

What 8 flashes means

Power off failure: the control detected a flame signal when it shouldn't.

Likely causes

Pilot not going out when the knob is off
Thermopile still hot

Safe first checks

Turn the knob to OFF and look through the viewport. If there's no pilot flame, wait 10 minutes and relight following the label.

When to stop

If a pilot flame is still there with the knob OFF, turn the main gas supply off and call a qualified technician; the gas control needs replacing.

Checked against: A.O. Smith Residential Standard Gas Water Heater Service Handbook: diagnostic flash codes. Codes can differ by model and year, so confirm with your owner's manual.