A.O. Smith and State gas water heater: what the status light means
If you smell gas
Stop: do not relight or troubleshoot anything. A.O. Smith’s own words (Residential Gas Water Heater Installation Instructions and Use & Care Guide 100263112, cover page):
- Do not try to light any appliance.
- Do not touch any electrical switch; do not use any phone in your building.
- Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s instructions.
- If you cannot reach your gas supplier, call the fire department.
Calling from a neighbor’s phone means leaving the building first.
A.O. Smith’s standard atmospheric gas water heaters with the flammable-vapor-resistant (FVIR) system have an electronic gas control valve powered by a thermopile in the pilot flame, with a status light on the valve. Its Use & Care Guide says the light flashes once every three seconds when the pilot is lit and the valve has found no problem; more flashes than that are a code from its Status Light Code Troubleshooting Chart: 2, 4, 5, 7 or 8. State, another A.O. Smith brand, prints the same codes with the same meanings in its service handbook for residential standard gas water heaters, so each code has one page here.
The status light is on the gas control valve, the box on the front of the tank with the gas control knob (OFF, PILOT and temperature settings) and the igniter button. The model and serial number are on the water heater’s data plate. A.O. Smith’s own pilot-lighting article says the light must flash once per second, while the Use & Care Guide’s chart says once every three seconds; these pages follow the chart in the manual, which is the one that lists the codes.
Status light off (0 flashes)
The pilot light is not lit, or there is not enough power (millivolts) from the thermopile to keep it lit.
A fault or shutdown: see the page for the owner steps and when to call for service.
Status light on solid
The pilot was lit but is now off, and the thermopile is still cooling down.
A fault or shutdown: see the page for the owner steps and when to call for service.
1 flash every 3 seconds
Normal operation: the pilot is lit and the gas control valve has not detected any problem.
Normal operation.
2 flashes, then a pause
Insufficient power (millivolts) reaching the gas control valve/thermostat from the thermopile.
A fault or shutdown: see the page for the owner steps and when to call for service.
4 flashes, then a pause
High water temperature has activated the overheat sensor (State’s handbook calls it “temperature exceeded (ECO activated)”).
A fault or shutdown: see the page for the owner steps and when to call for service.
5 flashes, then a pause
Sensor failure: the temperature sensor in the gas control valve has failed.
A fault or shutdown: see the page for the owner steps and when to call for service.
7 flashes, then a pause
Gas control valve/thermostat failure (State’s handbook: “internal control failure”).
A fault or shutdown: see the page for the owner steps and when to call for service.
8 flashes, then a pause
This appears only after the gas control knob has been turned off: either the thermopile kept making power because it did not cool as quickly as expected, or the pilot kept burning because the pilot valve is stuck open.
A fault or shutdown: see the page for the owner steps and when to call for service.
A.O. Smith’s manual: “Installation and service must be performed by a qualified installer, service agency or the gas supplier.” Its Technical Assistance Hotline is 1-800-527-1953; have the model and serial number from the data plate ready.
Sources
A.O. Smith’s own manuals and pages only, read on the date shown. Nothing here comes from forums or third-party “codes explained” sites.
- A.O. Smith: Residential Gas Water Heater Installation Instructions and Use & Care Guide (100263112, January 2015), “Status Light Code Troubleshooting Chart” and “Lighting the Pilot” — A.O. Smith residential atmospheric gas water heaters with the Flammable Vapor Ignition Resistant safety system and an electronic gas control valve. assets.hotwater.com Checked 2026-09-29.
- State Water Heaters (A.O. Smith): Residential Standard Gas Water Heater Service Handbook (327306), “Diagnostic Flash Codes” — State residential standard (atmospheric) gas water heaters with the electronic gas control valve/thermostat — a handbook written for qualified service professionals. www.statewaterheaters.com Checked 2026-09-29.