If your pilot light keeps going out, you are not alone. This common furnace and water heater problem can be frustrating-especially when it’s cold outside and in the middle of the night. Your pilot light is responsible for lighting your system’s burners, and if it won’t stay lit, neither will your heat-or hot water.
Fortunately, a flickering or completely extinguished pilot light usually indicates a problem that is manageable to solve. In this comprehensive guide, we’ll explain why your pilot light keeps going out, what you can safely do to fix it, and when to call a professional.
What is a Pilot Light and Why It Matters
The pilot light is the small, always-burning flame that ignites your furnace or water heater’s main burners.
On older gas systems, it’s lit continuously. When your thermostat calls for heat, the gas valve opens and the pilot light ignites the burners.
If the pilot goes out, your appliance can’t start. Most modern systems use electronic ignition instead, but many older furnaces and water heaters still use a standing pilot light.
Is It Normal for a Pilot Light to Go Out Occasionally?
It can—and does—happen from time to time, and not necessarily because of serious reasons: a strong draft, a temporary loss of gas pressure, or even a bump when cleaning may extinguish the flame.
However, if your pilot light itself repeatedly goes out, that is a different story. Continuous outages mean deeper issues with the thermocouple, gas valve, or air supply.
Also read: Furnace Ignitor Lights But No Flame
Common Reasons the Pilot Light Keeps Going Out
Below are the most common causes—and what each one means for your system.
1. Faulty Thermocouple
What it is:
The thermocouple is the small copper rod that detects the heat from the pilot flame. It acts as a safety device and shuts off the flow of gas when there is no flame.
What happens:
First, if the thermocouple is dirty, bent, or malfunctioning, it can’t sense the flame. It then shuts off gas flow-even if the pilot light is still burning-causing it to go out.
How to repair it:
1. Shut off the gas, allowing everything to cool.
2. Gently clean the thermocouple tip with fine sandpaper or a soft brush.
3. Make sure it’s positioned correctly—about ½ inch from the flame.
4. It should be replaced if it’s cracked, loose, or corroded.
When to call a professional:
If cleaning doesn’t work, have an HVAC or plumbing technician replace the thermocouple and check the gas valve connection.
2. Dirty Pilot Orifice
What it is:
Dust, rust, and soot might block the small opening that allows gas to flow and create the pilot flame.
What happens:
A partially blocked orifice can result in a weak, yellow, or flickering flame which does not generate enough heat to keep the thermocouple engaged—hence, the pilot goes out.
How to fix it:
1. Turn off the gas supply.
2. Use a needle or fine wire to carefully clean the orifice.
3. Do not apply too much pressure or blow into the tube as this could actually force any debris deeper inside.
4. Relight and check to see that the flame burns steady and blue, not yellow or orange.
3. Drafts or Airflow Issues
What happens:
A sudden puff of air, an open window nearby, or a badly sealed vent can snuff out the pilot light, mainly in basements, attics, and garages.
How to fix it:
• Seal air leaks around doors, vents, or flue pipes.
• Make sure the appliance isn’t located directly under a vent or fan.
• Check that the flue or chimney is properly connected and not drawing excessive air.
4. Gas Supply or Pressure Problems
What happens:
If gas flow is inconsistent, then the pilot flame will not get the fuel required to stay lit. This could be because of low gas pressure, an obstruction in the line, or a malfunctioning gas regulator.
How to check:
• Make sure your gas supply valve is fully open.
• Check that other gas appliances, such as a stove, are working properly.
• If you notice weak flames, hissing, or irregular operation, it may point to an issue with your gas line or utility supply.
Important:
Never try to regulate gas pressure on your own. Call your gas provider or a licensed technician.
5. Faulty Gas Valve
What it is:
The gas control valve controls gas flow to both the pilot and main burners. It will eventually fail due to internal wear or debris.
Signs
• Pilot won’t light at all.
• Pilot lights but won’t stay on.
• You smell gas around the valve – this could be an indication of a leak at this area.
Solution:
Switch off the system and seek immediate professional assistance. Gas valves are safety-critical components that require proper calibration and testing.
6. Moisture or Rust in the System
Condensation, humidity, or leaks can corrode the pilot assembly and thermocouple, weakening the flame and causing frequent outages.
Fix:
• Keep the area around your furnace or water heater dry and well-ventilated.
• Have rusted or corroded parts replaced promptly.
• If water is found pooling around the base, find the source of the leak and repair it.
7. Incorrect Flame Size or Color
The pilot flame ought to burn strong, steady, and blue with a small yellow tip.
If the flame is mostly yellow or very small, it is not producing enough heat to keep the thermocouple engaged.
Fixes
• Clean the pilot assembly.
• Adjust the flame height with the pilot adjustment screw, if your model allows.
• If the problem continues, then a technician should inspect the gas pressure and orifice condition.
8. Faulty Electrical Components- for Newer Systems
Some newer furnaces use electronic ignition instead of a standing pilot light. These systems can exhibit ignition control or sensor failures that mimic pilot issues.
If you have an igniter instead of a manual pilot, you will need an HVAC professional who can test the control board, igniter, and flame sensor for you.
Also read: Gas Furnace Short Cycling
Step-by-Step Guide: How to Relight a Pilot Light Safely
If your pilot light has gone out, follow these steps carefully:
1. Shut off the gas supply by turning the knob on the gas control valve.
2. Wait at least 5 minutes to enable the lifting gas to clear.
3. Locate the pilot assembly and find the “Pilot” position on the control knob.
4. Press the knob down and use a long lighter or match to light the pilot.
5. Continue holding the knob for 30–60 seconds after the flame lights.
6. Release slowly while observing if the flame remains lit.
7. If it goes out again, repeat once. If it still won’t stay lit, stop and call a technician.
Safety Reminder:
If you smell gas or hear a hissing sound, do not relight the pilot. Leave the area immediately and contact your gas provider or emergency services.
What the Pilot Flame Should Look Like
A healthy pilot flame should:
• Burn blue with a small yellow tip.
• Steady, not flickering or wavering
• Envelop the thermocouple tip fully.
If your flame is weak, yellow, or sputtering, this is a sign of dirt, low gas pressure, or improper adjustment.
How to Keep Your Pilot Light from Going Out
Most pilot light problems can be avoided through regular maintenance and attention to the matters of airflow and cleanliness.
1. Schedule Annual Maintenance
Have your furnace or water heater inspected every year by a professional. A technician will clean the burner assembly, check the thermocouple, and assure safe operation.
2. Keep the Area Clean
Dust, lint and pet hair can easily block airflow around the pilot assembly. Vacuum the area regularly.
3. Keep Proper Ventilation
Make sure your appliance has a good supply of air; its vents or flues are not blocked.
4. Check for Moisture
Prevent any leakage or condensation around the appliance: Water causes rust and may put out the fire.
5. Replace Aging Components
Thermocouples and pilot assemblies wear out over time. It is inexpensive to replace them every few years, and it can prevent unexpected outages.
When to Call in a Professional
Call a licensed HVAC or plumbing technician if:
• The pilot light repeated goes out although cleaned.
• The flame is weak, irregular, or yellow.
• You smell gas or notice soot buildup.
• The gas valve or thermocouple appears damaged.
• You’re uncomfortable handling gas components yourself.
Professionals can check gas pressure, replace bad components, and ensure that your appliance is up to safety standards.
SAFETY WARNING: Don’t Ignore a Failing Pilot Light
It’s not only frustrating but quite dangerous when a pilot light keeps going out. Persistent outages could mean gas leakage, poor ventilation, or problems in combustion.
Ignoring these signs can lead to a carbon monoxide buildup or inefficient operation. A carbon monoxide detector should always be used near gas appliances for safety.
Also read: Flame Sensor Furnace
Troubleshooting Summary Table
| Symptom | Likely Cause | Fix |
| Pilot won’t stay lit | Dirty thermocouple | Clean or replace thermocouple |
| Weak yellow flame | Clogged pilot orifice | Clean orifice and adjust flame |
| Pilot goes out in wind | Draft or vent problem | Seal leaks, redirect airflow |
| Pilot won’t light at all | Faulty gas valve | Call technician for replacement |
| Frequently need to relight | Insufficient gas pressure | Have gas supply checked |
Final Thoughts
If the pilot light constantly goes out, don’t just keep relighting it, find out why. In most cases, it is due to a dirty thermocouple, weak flame, or draft problem.
You are often able to clean or adjust the pilot yourself safely, but persistent problems or gas smells require professional help.
Keeping the pilot assembly clean, having proper airflow, and scheduling annual service will ensure your system works well and safely throughout the year.
