The short answer
On most gas water heaters in Northern Virginia, the status light on the gas control should blink slowly, about once every three seconds. That means the pilot is lit and the control is happy. Quick flashes with a pause between them are a fault code. Two flashes usually means a weak pilot, four means the water got too hot and the control shut itself down, and seven or eight means the gas control itself needs a look.
Find the light and count it
The light is on the gas control, the box on the front of the tank where the gas line goes in and the temperature knob sits. Watch it for a full minute. Count the flashes between pauses, count a second round to be sure, and take a short video. Rheem, A. O. Smith and Bradford White tanks mostly use the same family of gas controls, so the codes line up.
Swipe to see all columns →
Swipe to see all columns →
| What you see | What it means | What to do |
|---|---|---|
| One slow blink about every 3 seconds | Normal. The pilot is lit and the control is fine | Nothing |
| No light | The pilot is out, or the control is off | Relight it by the label on the tank. If it won’t stay lit, call |
| Light on solid, not blinking | The pilot just went out and the control is cooling down | Wait 10 minutes, then relight |
| 2 flashes | Weak pilot signal: the thermopile is low, or the pilot flame is small or dirty | Call. Usually a thermopile or a pilot cleaning |
| 4 flashes | The water got too hot and the high-limit safety opened | Turn it off and call. A. O. Smith’s manual says the gas control gets replaced |
| 5 flashes | The temperature sensor failed | Call |
| 7 flashes | The gas control failed | Call. The gas control gets replaced |
| 8 flashes | Flame seen with the knob turned off | Leave it off, don’t relight, and call |
Bradford White’s ICON control matches this chart on 2, 4 and 5 flashes. On the older ICON 1.0, 3 flashes means the control didn’t see the water warm up, 6 means the leak sensor found water, and 7 and 8 match the chart. Brand by brand: Bradford White codes (and the date code), A. O. Smith codes, Rheem blinking light codes (and how old a Rheem is), Rheem troubleshooting, Rheem heat pump water heater codes and a Rheem electric tank that stopped heating. Brand pages: Rheem, A. O. Smith, Bradford White.
$99 Water Heater Flush
We drain and flush the tank, check the anode rod and test the relief valve, then go through the house's plumbing with photos, included. See the flush
Want your own number before anyone comes out? The water heater estimator prices your house in a few questions.
Relighting the pilot
Every tank has the steps printed on its label, and they’re worth following exactly. If you smell gas, don’t relight anything: leave the house and call the gas company from outside. If the pilot lights and goes out again when you let go of the knob, the thermocouple or thermopile isn’t holding it, and that’s a part, not a technique problem. Here’s how to light a water heater pilot step by step, the usual causes when it keeps going out, and our Rheem pilot light post with photos. Rheem troubleshooting covers the rest of what a tank can do.
Power vent water heaters
A power vent tank has a fan on top and a white PVC pipe running outside. It has its own codes, mostly about the fan and the vent, because the burner won’t light until the fan proves the vent is clear. Here’s what a power vent water heater looks like. On Rheem and A. O. Smith power vents:
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Swipe to see all columns →
| Flashes | What it means |
|---|---|
| 2 | The pressure switch is stuck closed before the fan starts |
| 3 | The pressure switch or the blower’s thermal switch is open: a blocked vent, a weak fan, a cracked hose |
| 4 | The thermal cutoff tripped: too hot |
| 6, then 1 | It tried to light and didn’t |
| 6, then 3 | It lit and the flame went out |
| 7 | The flammable vapor sensor tripped: gasoline or paint thinner near the tank, or a failed sensor |
On a Bradford White power vent, one flash a second means a weak pilot, 8 then 1 means the flammable vapor sensor is out of spec, and 8 then 2, 3 or 4 point to gas valve faults. A snowdrift over the vent pipe outside throws a vent code on any brand, so check that first after a storm.
Tankless codes are numbers
A tankless shows a code on its front panel instead. On a Navien, E003 means it tried to light and couldn’t. On a Rinnai, code 11 means the same thing, and LC means scale has built up in the heat exchanger and it’s due for a descale. Northern Virginia’s hard water gets there faster than people expect. Our descale is $300, regularly $350. More on tankless problems and tankless maintenance.
When the tank is the problem
A gas control or a thermopile is a normal repair on a young tank. On a tank that’s 10 to 12 years old, it’s worth weighing the repair against a new one before you spend on parts. The year is on the label, and here’s how long a water heater lasts. If you go new, the water heater estimator shows your installed price first, and $500 comes off it.
On a tank with years left, the water heater flush is $99 (normally $199): we drain and flush the tank, check the anode rod and test the relief valve. Sediment is what overheats the bottom of the tank. The maintenance guide has the rest, and every water heater service is on our water heaters page.
Book it
A plumbing diagnosis visit is $49, or $250 after hours, and you get the price of the fix before we start. Call (703) 997-9757, day or night, or book the water heater flush from goswiftpro.com/cookiesoffer by November 30 and a box of warm MOLTN cookies comes with it. Every current deal is on our offers page. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Questions people ask
What do 2 flashes on a water heater mean?
A weak pilot signal. The thermopile isn’t making enough power, or the pilot flame is small or dirty. It usually needs a thermopile or a pilot cleaning.
Is it normal for a water heater light to blink?
Yes, if it’s one slow blink about every three seconds. That means the pilot is lit and the control is fine. A counted pattern of quick flashes is a fault code.
Why is there no light on my water heater?
The pilot is out, or the gas control is turned off. Relight it by the label on the tank. If it won’t stay lit, the thermocouple or thermopile usually needs replacing.
What do 4 flashes mean on a water heater?
The water got too hot and the high-limit safety opened. On many controls that safety is built into the gas control, so the control gets replaced. Turn it off and call instead of relighting it.
