Water Heater Pilot Light Keeps Going Out? Common Causes

The pattern usually goes like this: you wake up to cold water, relight the pilot following the label on the tank, it works for a day or a week, and then it's out again. Or it lights, you let go of the button, and it dies within seconds. Both are among the most frequently asked water heater questions online, and the answers from working plumbers point to the same short list of causes.

First, a safety rule: if you smell gas (a rotten-egg odor) near the water heater, do not try to relight anything. Leave the house, and call the gas utility or 911 from outside. See our guide to gas leak warning signs.

If it goes out the moment you release the button

This is the classic thermocouple (or thermopile) symptom. The thermocouple is a small sensor that sits in the pilot flame and tells the gas valve it is safe to keep gas flowing. If it's worn, dirty or not sitting in the flame, the valve shuts the gas off as soon as you stop holding the button. Plumbers commonly suggest holding the pilot button for the full time the manufacturer's label specifies before letting go; if it still won't stay lit after that, the sensor is the likely suspect. It's an inexpensive part, but correct placement in the flame matters.

If it stays lit for hours or days, then goes out

An intermittent pilot outage usually points to one of these:

A clogged combustion air screen. Many modern gas water heaters have a flame-arrestor screen at the bottom. Dust, lint and pet hair — very common in Torrance garages where the heater sits next to the washer and dryer — can starve the burner of air, and the pilot snuffs itself out. This is one of the most-cited causes in homeowner forums.
A weak or dirty pilot flame. A small, yellow or lifting flame doesn't heat the sensor properly. That can come from a partly blocked pilot orifice.
Drafts or venting problems. A garage door, a nearby vent or a flue that isn't drawing properly can push or pull the flame off the sensor.
A tripped high-temperature limit. Some units shut down if the water overheats. If that's happening repeatedly, the controls need attention, not repeated relighting.

What a homeowner can safely check

Make sure the gas control knob was turned from "Pilot" back to "On" after relighting — an easy step to miss.
Look for dust or lint buildup around the base and air intake and keep the area clear. Follow the manufacturer's instructions for the model; don't take apart the burner assembly.
Note whether other gas appliances are working normally. If none are, the problem may be supply, not the heater.
Look at the flame through the sight window if your model has one: a steady blue flame is what you want.

When to stop relighting and call

If the pilot has gone out more than twice, stop. Repeated relighting doesn't fix a failing thermocouple, a bad gas valve or a venting problem, and venting problems in particular are a safety issue, not an inconvenience. Also call if you see scorch marks near the burner access, the flame is yellow and lazy, or the heater is old enough that a larger repair may not make sense — see how long water heaters last. Gas valve and burner work belongs with a licensed plumber.

Is this a repair or a replacement?

A pilot problem on its own is usually a repair. It becomes a replacement conversation when it shows up alongside other age signs — rust at the base, rumbling, or leaks. Our guide to a leaking water heater covers that side.

Getting hot water back

If your pilot keeps going out in Torrance, call (209) 860-5004 or see water heater repair in Torrance. For a no-hot-water situation after hours, see emergency water heater repair.