Why Does My Furnace Pilot Light Keep Going Out?

You relight your water heater, wait for the burner to kick on, and everything seems fine, until the pilot goes out. If your water heater pilot light keeps going out, the problem could be as simple as a dirty pilot opening or as serious as an issue with the gas supply.

Knowing what causes repeated pilot light failure can help you determine what you can safely check yourself and when it’s time to call a professional.

• A failing thermocouple, dirty pilot assembly, drafts, or gas supply problem can cause a water heater pilot light to repeatedly go out.
• Never attempt DIY repairs involving gas lines, gas pressure, or a gas control valve.
• Regular water heater maintenance can help identify worn or dirty components before they leave you without hot water.

On a traditional gas water heater, the pilot light is a small flame that stays lit so it can ignite the main burner when the tank needs to heat more water.

Gas travels through a pilot tube to the pilot orifice, where it produces the pilot light flame. A thermocouple sits near the flame and acts as an important safety feature. When it senses sufficient heat from the pilot, it signals that gas can safely continue flowing. If the flame goes out, the thermocouple helps shut off the gas.

Some systems use a thermopile, while newer water heaters may use an electronic ignition system or hot surface igniter instead of traditional pilot lights.

Depending on the model, you may also have a status light that displays information about the water heater's operation or potential problems.

No hot water or hot water running out fast is the most obvious sign, but it isn't the only one. Check your water heater if you notice:

• No hot water or inconsistent temperatures
• A pilot light that won't stay lit
• A weak or flickering flame
• A yellow pilot flame instead of a steady blue flame
• Soot or black marks near the burner assembly
• Repeated difficulty relighting the pilot
• An unusual status light or error code

A yellow flame, soot, or other signs of improper combustion should be evaluated by a licensed technician.

If you smell gas, don't attempt to relight the water heater. Leave the area and follow appropriate gas-emergency procedures.

The thermocouple is one of the most common causes of pilot light failure. Because it sits close to the flame, carbon buildup and normal wear can affect its ability to sense heat. If it doesn't detect the pilot flame correctly, the safety system may shut off gas flow, even when the flame is present.

A thermocouple can also become bent or positioned incorrectly.

Light surface buildup may sometimes be addressed during routine maintenance, but a damaged or failing thermocouple typically requires replacement.

Pilot orifice clogging can restrict gas flow and produce a weak, unstable flame. A dirty pilot tube can cause similar problems.

Some DIY instructions recommend compressed air or a thin wire for pilot tube cleaning. However, pushing objects into a pilot opening can damage or enlarge the orifice. If cleaning requires disassembling the pilot assembly or manipulating gas components, leave the job to a professional.

A pilot flame needs adequate combustible air, but too much uncontrolled airflow can blow it out.

Draft-related pilot light issues can sometimes come from open doors, nearby fans, or changes around the water heater. Problems with the venting system or exhaust pathway can also affect combustion and should receive professional attention.

Don't attempt to solve recurring drafts by blocking vents or reducing the water heater's required combustion air. Proper airflow is necessary for safe operation.

Low gas pressure or an interrupted gas supply can prevent the pilot from staying lit.

Possible sources include the gas supply valve, gas regulator, gas control valve, gas supply line, or a broader utility problem. Damaged gas tubing, kinked hoses where applicable, or other restrictions may also interfere with gas flow.

Gas pressure problems aren't a DIY project. Have a certified technician diagnose suspected gas supply issues.

The gas control valve regulates gas flowing to the pilot and main burner.

If the valve malfunctions, the pilot may not receive consistent fuel. Because the component directly controls combustible gas, testing or replacing it should be handled by a licensed technician.

Corrosion, physical damage, carbon buildup, or problems around the burner assembly may interfere with reliable operation.

Blocked or improperly functioning venting can create more serious safety concerns. A professional can perform a burner assembly inspection and venting system inspection to determine whether the water heater is operating correctly.

Before relighting the pilot, read the owner's manual and the lighting instructions printed on the water heater. Procedures vary by manufacturer and model.

For many traditional gas water heaters, the basic process involves:

1. Turn the gas control knob to OFF.
2. Wait the amount of time specified by the manufacturer to allow residual gas to dissipate.
3. Turn the control knob to PILOT.
4. Press and hold the pilot knob or appropriate control.
5. Press the ignitor button if the unit has one.
6. Continue holding the control for the specified time.
7. Release it and confirm that the pilot remains lit.
8. Turn the control to its normal operating position.

Older models may require a long lighter instead of an integrated ignite button. Never improvise if you're unsure of the correct procedure.

If the pilot immediately goes out again, don't repeatedly attempt to relight it. That indicates another problem needs to be diagnosed.

Homeowners can perform some basic hot water heater maintenance at home without taking apart the water heater. Start by checking the owner's manual and any available resources by model. Confirm the gas supply valve hasn't accidentally been turned off and look for an error or status light.

You can also visually inspect the area for obvious drafts, debris, corrosion, or physical damage.

Avoid removing or modifying gas components with a screwdriver, cleaning a thermocouple with fine sandpaper, or attempting gas valve repairs unless the manufacturer's instructions specifically identify the procedure as homeowner maintenance and you're qualified to perform it.

When in doubt, call a professional.

Regular maintenance can reduce the likelihood of unexpected water heater problems. Depending on your system, professional maintenance may include:

• Annual maintenance checks
• Burner assembly inspection
• Thermocouple cleaning or testing
• Pilot tube cleaning
• Gas line inspection
• Venting system inspection
• Exhaust pathway cleaning
• Safety feature testing
• Sediment build-up flushing

Sediment is especially relevant for Las Vegas homeowners because hard water minerals can accumulate inside conventional tank water heaters. Routine flushing can help control sediment buildup and support efficient operation.

Maintenance also gives a technician an opportunity for early detection of corrosion and worn components.

If your water heater pilot light keeps going out, schedule professional service. Contact a plumbing professional if you notice a yellow or flickering flame, soot, corrosion, physical damage, repeated ignition problems, or signs of a gas supply issue.

Problems involving the gas regulator, gas pressure, gas control valve, burner assembly, or venting system should always be handled by a qualified professional.

A pilot light that won't stay lit can quickly turn into a frustrating lack of hot water, and the underlying cause shouldn't be ignored.

Dr. Cool provides water heater services, including repairs, maintenance, and installation for homeowners throughout Las Vegas and surrounding communities. Our licensed technicians can diagnose pilot light problems, inspect your water heater, and recommend the appropriate repair or replacement when necessary.

Call Dr. Cool at (702) 608-6913 or schedule your appointment online today.