Most recurring pilot outages trace back to a failing thermocouple or thermopile, a clogged pilot orifice, a faulty gas control valve, or poor combustion air in the room. If you smell gas or suspect carbon monoxide, skip the troubleshooting and ventilate the space immediately, then call your gas company or emergency services before touching anything.
TL;DR:
- During a safe relight, turn the control to off, wait about five minutes, then hold the pilot control down for 60 to 90 seconds before releasing it.
- If the pilot dies as soon as you release the knob, suspect the thermocouple; dust or webbing around the orifice can instead starve the flame.
- Many manuals limit relighting to three attempts, with at least 10 minutes between tries; stop sooner if the status light signals a lockout or the flame arrestor is damaged.
- Repeated outages after new ventilation work, or headaches and dizziness that ease outdoors, call for a licensed technician with combustion testing equipment.
Table of Contents
- Common Causes Behind a Pilot That Won't Stay Lit
- How to Relight a Pilot Safely
- Troubleshooting Checklist Before You Call a Pro
- When Combustion Safety Means Calling a Technician
- Preventative Maintenance That Reduces Pilot Outages
- Field Notes From a Technician's Perspective
- Deciding Your Next Step
- How We Can Help With a Pilot Light That Won't Stay Lit
- FAQ
- Sources
Common Causes Behind a Pilot That Won't Stay Lit
A pilot light that keeps dying almost always points to one part failing to do its job, or to the room itself not giving the flame what it needs.
The thermocouple or thermopile is usually the first suspect. This small sensor sits in the pilot flame and tells the gas valve that a flame is present. When it wears out, you'll often notice the pilot stays lit while you hold the knob down, then dies the second you let go. That's a classic failure signature, not a fluke.
A clogged pilot orifice or dirty pilot tube is another frequent culprit. Dust, soot, or even a tiny spider web can choke the small opening that feeds gas to the pilot, starving the flame until it sputters out.
A gas control valve or inconsistent gas pressure can also cause intermittent pilot behavior. If other gas appliances in the house are acting oddly at the same time, the problem may be upstream of the heater entirely.
Drafts and insufficient combustion air matter more than most homeowners expect. Tight, well-sealed homes and newly installed exhaust fans can starve a combustion appliance zone of fresh air, a condition building science professionals call CAZ depressurization. It can snuff a pilot repeatedly.
Finally, some outages aren't failures at all. Safety systems like Flammable Vapor Ignition Resistant (FVIR) designs and flame arrestors are built to shut the pilot off on purpose when they sense unsafe combustion conditions, according to manufacturer guidance.
- A thermocouple that holds flame only while the knob is pressed usually needs replacement.
- Soot or webbing near the pilot tube often means it's time for a careful cleaning.
- Multiple gas appliances misbehaving together points to a supply issue, not the pilot itself.
How to Relight a Pilot Safely
Before you do anything else, smell the area around the appliance. If you catch even a faint gas odor, do not attempt to light the pilot. Ventilate the room and call your gas utility instead.
When the air is clear, most manufacturers walk you through a similar sequence:
- Turn the gas control knob to "off" and wait about five minutes to clear any residual gas.
- Turn the knob to "pilot" and press it down.
- Light the pilot with the igniter or a long lighter while continuing to hold the knob down.
- Hold the knob for 60 to 90 seconds, since many modern water heaters require this hold time to let the thermocouple warm up and to clear air from the gas line.
- Release the knob slowly and check that the pilot stays lit on its own.
One manufacturer specification worth knowing: many owner manuals limit relight attempts to three tries with at least a 10-minute wait between each attempt. Respecting that interval protects the control valve and gives you a cleaner read on whether the problem is simple or mechanical.
Do not keep relighting if you notice discolored flame trap screens, a status light signaling an FVIR lockout, or any lingering gas smell. Those situations call for a technician, not another attempt.
Troubleshooting Checklist Before You Call a Pro
Work through these checks in order, starting with the simplest and safest.
- Look at the flame. A healthy pilot burns soft blue. Orange, yellow, or flickering flames suggest contamination or airflow problems.
- Check the pilot's position and surroundings for dust, lint, or debris that could be blocking airflow or the orifice itself.
- Clean the pilot orifice and sight port gently with a soft brush or compressed air if you see buildup, then stop and call a technician if the flame still won't hold.
- Watch the thermocouple's behavior. If the pilot holds only while you press the knob and dies on release, that part likely needs replacing.
- Confirm gas supply to other appliances. If your stove or furnace also seems underpowered, the issue may be a supply or valve problem rather than the pilot assembly.
- Rule out nearby exhaust fans or new ventilation that might be pulling combustion air away from the appliance.
Pro Tip: Wait at least a minute between adjustments to the thermocouple or thermopile before testing again. Testing too soon after cooling or heating it gives a false reading and can lead to an unnecessary part replacement.
If outages continue after working through this list, the problem is likely venting, combustion air, or valve electronics. This is territory better suited to a licensed technician.
When Combustion Safety Means Calling a Technician
Some checks simply aren't DIY territory. Combustion appliance zone testing, which measures flue spillage and carbon monoxide over a sustained window, requires calibrated instruments and training that go beyond a homeowner's toolkit, per building science safety standards.
Call a professional now if you notice any of the following:
- Any smell of gas, however faint.
- Headaches, dizziness, or nausea that ease when you leave the house, which can signal carbon monoxide.
- Discolored or damaged flame arrestor screens.
- Pilot outages that started right after new exhaust fans, windows, or insulation work.
- Repeated failed relights even after following the manual's timing and retry limits.
A technician's visit typically includes carbon monoxide measurement, a flue spillage test held for more than 60 seconds, a flame trap inspection, and diagnostics on the gas valve and controls, the kind of combustion-safety check that periodic professional servicing is built around.
Preventative Maintenance That Reduces Pilot Outages
A little seasonal upkeep goes a long way toward keeping a pilot lit reliably.
- Replace or clean furnace filters regularly and keep the area around burners and combustion chambers free of dust.
- Schedule an annual inspection that includes combustion analysis and a venting check, not just a filter swap.
- Flush your water heater periodically to reduce sediment buildup that can affect burner performance over time.
- If your pilot-equipped unit is older than roughly 20 to 25 years, recurring outages are often a sign the appliance itself is due for replacement rather than another repair.
Field Notes From a Technician's Perspective
Years of service calls teach you a few tricks that manuals skip. Dimming the room lights makes a weak pilot flame or igniter spark much easier to spot, a habit echoed in manufacturer support guidance for units without a visible status light. Giving the thermocouple or thermopile a full 60 to 90 seconds to warm during relighting, and a cool-down pause before retesting, prevents the kind of false "it's broken" conclusion that sends people shopping for parts they don't need.
Pro Tip: If a pilot relights fine but dies again within a day, don't keep repeating the same attempt. Pause, note what changed in the room (a new fan, a closed vent), and bring that detail to whoever inspects the unit.
— Aaron Waller, General Manager
Deciding Your Next Step
If this is a one-time incident, relight the pilot per the manual and keep an eye on it for a day or two. If it keeps happening, clean the pilot assembly or consider replacing the thermocouple. If outages continue, or you notice any gas smell or signs your water heater needs attention, stop troubleshooting and call a licensed technician.
How We Can Help With a Pilot Light That Won't Stay Lit
We handle water heater repair, thermocouple replacement, and combustion-safety inspections, and we send a real local technician, not an automated phone tree, to figure out what's actually going on.
If your pilot keeps going out after you've tried the basics, we can run a proper combustion-safety check and fix the part that's actually failing. Book a service visit and we'll get a licensed technician out to take a look.
FAQ
How do you fix a pilot light that keeps going out?
Clean the pilot orifice of dust or debris, then check whether the flame holds only while you press the control knob, which points to a worn thermocouple. If cleaning and a part replacement don't solve it, the cause is likely a venting or gas-valve issue that needs a professional diagnosis.
How to clean a thermocouple on a gas heater?
Turn off the gas supply first, then gently wipe the thermocouple's tip with fine emery cloth or a soft cloth to remove soot and oxidation. Let it rest for about a minute before testing again, since testing too soon after handling it can produce a misleading result.
Why does my furnace pilot light randomly go out?
Random outages often come from drafts, a nearby exhaust fan pulling combustion air away from the unit, or a thermocouple that's starting to fail intermittently. Sealed, tightened homes can also starve the appliance of fresh air, a condition building science training programs address directly.
What could cause a water heater pilot light to keep going out?
A clogged pilot orifice, a weak thermocouple, or low gas pressure are the most common causes, but some units also include safety systems that shut the pilot off on purpose when they sense unsafe combustion. Manufacturer manuals describe these flame-trap safety features as protective, not a sign the pilot assembly itself is broken.
Sources
- How to light a pilot light
- Residential Gas Water Heater with the Flame Lock (owner manual)
- Get the Most from Your Gas Heating Dollar: Periodic Servicing of Gas Burners for Home Heating Helps Maintain Safety Save Gas and Cut Pollution
- HVAC - Combustion Safety | Building Science Education