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Ask John Furnace Pilot Light Flickering Main Image

Why Does the Pilot Light on My Furnace Keep Flickering?

John Turpin is our resident home service repair expert here at Service Direct. He’s got the knowledge and experience to help homeowners like you make sense of most home repair issues. And with Service Direct, we connect you with top-tier service professionals to help with any repairs needed.

Learn the Reasons Why Your Furnace Pilot Light Keeps Flickering

The pilot light in a furnace is a small flame that ignites the main burner, allowing the furnace to produce heat. It’s an important part of the furnace, but one that we often only think about when they become a problem.

At that point, you probably turn to the internet, frantically searching for a reason why you have a flickering furnace light. This is not normally a big problem but can be a cause for concern if the pilot light consistently flickers.

Don’t worry because we’re here to help you figure out why this is happening. In this article, we will explore some common reasons why the pilot light on your furnace may flicker and what you can do to resolve the problem.

Furnace Pilot Flickering Out
Don’t get left in the cold because of a faulty furnace pilot light.

Flickering Furnace Light: Common Reasons and Possible Solutions

Dirty or Clogged Pilot Orifice

One of the primary reasons for a flickering pilot light is a dirty or clogged pilot orifice. Over time, dust, debris, or rust particles can accumulate in the orifice, obstructing the flow of gas to the pilot light. This disruption in the gas supply can cause the pilot light to flicker or go out altogether. Cleaning the orifice using compressed air or a thin wire can often resolve this issue.

Thermocouple Issues

The thermocouple is a safety device that senses the pilot light’s flame and sends a signal to the gas valve to keep it open. If it’s faulty or not positioned correctly, it may not generate enough voltage to hold the gas valve open consistently. This can result in a weak or flickering pilot light. For this issue, you’ll need a trained technician to inspect and adjust the thermocouple or replace it if necessary.

Drafts or Improper Ventilation

Drafts or improper ventilation near the furnace can disrupt the stability of the pilot light flame. If there’s a strong draft or airflow in the area, it can cause the flame to flicker or go out. Ensure that windows, doors, and vents are properly sealed. Also, make sure there are no obstructions around the furnace. Don’t forget to check the flue pipe or chimney to ensure it’s clear and properly functioning.

Gas Pressure Issues

Another possible reason for a flickering furnace light is a problem with gas pressure. In some cases, low gas pressure can result in an insufficient amount of gas reaching the pilot light, leading to it flickering or going out. This can be caused by issues with the gas supply, such as a faulty regulator or a problem with the gas line. In this case, it’s important to have a professional technician inspect the gas pressure and promptly address any issues with the gas supply system.

Our resident home repair guru, John Turpin, has provided a list of common reasons why your pilot light is flickering out as well as some useful pro advice, tips and tricks to resolve.

Aging or Malfunctioning Components

Over the years, the components within the furnace can wear out or malfunction, leading to flickering furnace lights. This can include issues with the gas valve, ignition system, or pilot assembly. It would be tricky to pinpoint the exact root cause of the problem, especially if you’re unfamiliar with the inner workings of a furnace. In such cases, it’s recommended to have a professional technician diagnose and repair or replace the furnace’s faulty components to ensure safe and efficient operation.

Flame Sensor Malfunction

A malfunctioning flame sensor can also cause the pilot light to flicker. The flame sensor detects the presence of the flame and ensures it remains lit. If it’s dirty or covered in residue, it may not detect the flame properly. As a result, the pilot light flickers or flame is extinguished more often than not. Cleaning or replacing the flame sensor often resolves this issue.

Gas Supply Issues

Issues with the gas supply to the furnace can lead to a flickering pilot light. It could be due to a malfunctioning gas valve or a problem with the gas line itself. A technician will need to inspect and determine the root cause of the gas supply issue to restore the pilot light’s stable operation. Contact a professional HVAC technician to check your furnace.

Electrical Connection Problems

Faulty electrical connections within the furnace can also contribute to a flickering furnace light. Loose or corroded electrical connections can disrupt the flow of electricity to various components, including the pilot light. For this, you will need a professional technician to conduct a thorough inspection of the electrical connections to identify and rectify any issues.

Furnace Pilot Electric Problems
Qualified experts are experienced and trained to troubleshoot all aspects of your HVAC system.

DIY vs. Professional HVAC Service

When it comes to furnace pilot light repair and replacement, there are certain factors to consider when deciding between a do-it-yourself (DIY) approach or hiring a professional HVAC service. Here are some points to help you make an informed decision:


Safety should be your top priority. Dealing with gas appliances and pilot lights can be hazardous if not handled properly. If you are not experienced or knowledgeable about working with gas lines and combustion systems, it is generally safer to hire a professional. They have the necessary expertise and equipment to handle the job safely and minimize the risk of accidents or gas leaks.

The Complexity of the Issue

The complexity of the pilot light issue can also influence your decision. Simple tasks like cleaning the pilot orifice or relighting the pilot light may be within the capability of a DIYer. But if the issue involves more complex components, such as a faulty thermocouple, gas valve, or gas line, it is advisable to seek professional assistance. Professionals have the expertise to diagnose and repair these components effectively.

Warranty Considerations

If your furnace is under warranty, attempting DIY repairs or modifications may void the warranty. Manufacturers often require professional installation or repairs to maintain warranty coverage. It’s important to review the terms of your warranty and determine if DIY work is permitted without voiding the coverage.

Time and Resources

Assess the time and resources you have available. DIY repairs require research, acquiring the necessary tools, and investing your time and effort. If you have the knowledge, skills, and time to undertake the repair, and you are confident in your abilities, a DIY approach may be a viable option. But keep in mind that professional technicians are experienced and efficient, meaning they can often complete the job more quickly and with less hassle.

Long-Term Cost

While DIY repairs may seem cost-effective initially, incorrect repairs or installations can lead to more extensive damage or recurring issues down the line. Professional technicians have the expertise to diagnose the root cause of the problem accurately, ensuring a more long-term solution. They can also provide maintenance recommendations to help extend the lifespan of your furnace and prevent future issues, potentially saving you money in the long run.

If you have the necessary knowledge, experience, and time, and the issue is a simple task, a DIY approach may be feasible. Remember, when in doubt, it’s best to consult with a professional to ensure the job is done safely and effectively.

Advantages Of Hiring An Expert
Weigh up all the advantages and disadvantages of DIY before deciding to work on your HVAC system.

Flickering Furnace Light FAQs

Can I clean the pilot light orifice myself?

Cleaning the pilot light orifice requires careful handling and knowledge of furnace components. It’s recommended to have a professional HVAC technician clean the orifice to ensure proper cleaning techniques and safety.

Can a malfunctioning pilot light affect the furnace’s heating performance?

Yes, a flickering or unstable pilot light can affect the performance of the furnace. If the pilot light is not consistently burning, the main burner may not ignite, leading to inadequate heating or a complete lack of heat. Resolving the issue with the pilot light is crucial for proper furnace operation and heating efficiency.

Is it normal for a pilot light to flicker slightly during startup or shutdown?

A slight flickering of the pilot light during startup or shutdown can be normal. But if the flickering is inconsistent, excessive, or persists during the furnace’s operation, it’s a sign of a problem that needs attention. Regularly monitoring the pilot light’s behavior can help identify any unusual patterns, so you can address them before they get worse.

How often should I have my furnace inspected for pilot light issues?

It’s recommended to have your furnace inspected by a professional HVAC technician at least once a year, ideally before the start of the heating season. Regular maintenance and inspections can help identify and address potential issues with the pilot light or other furnace components.

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For safety, complex issues, warranty considerations, and peace of mind, we recommend you hire an HVAC expert using the phone number or form on this page.

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