State gas water heaters use AO Smith's LED indicator code system. A status LED on the gas control valve flashes in a pattern that identifies the fault. Count the flashes between pauses to read the code.
How to read the LED flash code
- Remove the burner cover or look at the gas valve from below
- Watch the status LED for several seconds
- Count the rapid flashes, then notice the pause
- The number of flashes before the pause is the code
- Pattern repeats every 5-10 seconds
The flash codes
| Flashes | Meaning | Action |
|---|---|---|
| 1 flash steady | Normal operation, unit ready | Status indicator — no fault |
| 2 flashes | Thermopile / pilot voltage low | Clean intake; replace thermocouple/thermopile |
| 3 flashes | Inlet thermistor (limited models) | Sensor test or replacement |
| 4 flashes | High-temp lockout / ECO trip | Check water flow, ECO reset, thermostat |
| 5 flashes | Vacuum switch / draft (atmospheric) or pressure switch (power vent) | Check chimney/vent for obstruction |
| 6 flashes | Flammable vapor sensor (FVIR) | Clear flammable vapors; reset |
| 7 flashes | Gas valve fault | Replace gas control valve |
| 8 flashes | Combustion air switch / intake blocked (gas units with intake screen) | Clean intake screen at base of unit |
How to reset
Three reset levels:
- ECO reset (electric units): red button on upper thermostat. Press firmly
- Gas valve reset: turn the gas knob to "Off," wait 5 minutes, turn to "Pilot" or "On"
- Power cycle: for electric or power-vent units, turn off breaker, wait 30 seconds, restore
If the same flash code returns within minutes of reset, the underlying fault is active. Work through the specific code's diagnostic walkthrough.
Electric unit diagnostics
Electric State units don't have an LED code system. Diagnosis is by:
- Breaker check (most common no-hot-water cause)
- ECO reset button on upper thermostat
- Multimeter test of upper and lower elements
- Multimeter test of upper and lower thermostats
Premier Hybrid heat pump diagnostics
Premier Hybrid units have a separate display panel on the front showing operating mode and any compressor or sensor faults. Common Premier Hybrid codes:
- P1 / P2 — temperature sensor fault
- F1 / F2 — control board fault
- HP — heat pump compressor lockout
- EL — element fault (resistance backup)
For Premier Hybrid faults, call State customer service at 1-800-365-0024 — heat pump diagnosis is more complex than tank diagnosis.
Bottom line
Gas units: count the LED flashes on the gas valve. Electric units: ECO reset + multimeter testing. Premier Hybrid: alphanumeric display + State support for complex faults.