Quick Recap
- The flame sensor is an essential safety component in your furnace.
- Signs of flame sensor failure include short cycling, yellow flames, and visible soot.
- Call an HVAC pro promptly if you suspect a problem with your furnace’s flame sensor.
What Does a Flame Sensor Do? A Simple Explanation for Homeowners
The flame sensor is one of the most important safety features of your home heating system. The role of the furnace flame sensor is to check whether there’s a flame burning in your furnace, and to immediately shut off the gas if it doesn’t detect a flame.
If there’s no flame and unburned gas is allowed to flow, it can lead to carbon monoxide poisoning and even an explosion. To prevent this risk, all modern gas furnaces come with a flame sensor to detect CO levels in gas appliances.
Warning Signs Your Furnace Flame Sensor Is Failing
Keep an eye out for these common bad flame sensor symptoms:
Furnace short cycling
When your furnace is running properly, it will usually turn on for about 15 minutes to heat your home before taking a break. Furnace short cycling occurs when your furnace shuts off after only a few minutes or seconds. If your flame sensor is failing, your furnace may try to turn on, run for a couple seconds, then immediately turn off again.
Insufficient heat
When there’s a flame sensor issue, your furnace won’t be able to run properly. You may have insufficient or no heat, or you may notice the furnace turning on but only blowing cold air.
Yellow burner flames
Your furnace has a little peephole that allows you to see the burner flame. When everything is working properly, this flame should be a bright, steady blue. Any other color is a warning sign. If the flame is yellow, or if it’s flickering and unsteady, chances are there’s an airflow issue or other problem that’s not allowing for complete combustion. This can lead to gas entering your home, so it’s important to call for prompt heating repairs.
Clicking noises
Your furnace will make a slight clicking noise when it tries to ignite. If the ignition is unsuccessful, your furnace may try multiple times, and you’ll notice frequent clicking sounds.
Visible cracks, dirt, or soot
Your flame sensor is protected by a porcelain casing. A simple visual inspection may reveal cracks in the porcelain that can indicate a problem. You can also inspect the sensor rod for soot, dirt, or other debris that can cause a faulty reading.
Common Causes of Flame Sensor Failure
If your furnace is not staying lit, it could be due to these common causes of flame sensor failure:
Dirty flame sensor
If your flame sensor becomes coated in soot or debris, it’s no longer able to take an accurate reading. Fortunately, dirty flame sensors can usually be cleaned quickly by an HVAC pro.
Aging furnace
Most gas furnaces last about 15 to 20 years. If your furnace is reaching the end of its expected lifespan, general wear and tear can lead to a variety of problems including flame sensor failure. If this is the case, it can be a good opportunity to upgrade to a high efficiency furnace and save on your monthly heating bill.
Moisture and corrosion
Flame sensors are typically made of metal, which is vulnerable to corrosion over time. The combustion process produces a small amount of moisture, which can lead to corrosion if there’s not enough airflow in the furnace.
Electrical issues
The flame sensor relies on an electrical connection with the furnace control board to provide an accurate reading. If there’s loose wiring, a faulty connection, or other electrical issues, this connection can get interrupted and lead to flame sensor failure.
Cleaning vs Replacing a Flame Sensor – What’s the Right Option?
Whether you should clean or replace a flame sensor depends on the type of problem. If the issue is a simple buildup of soot or debris, furnace flame sensor cleaning is the quickest and most cost-effective solution. However, if it’s worn or corroded, it may be time for flame sensor replacement. Your HVAC pro can diagnose the issue, and they may suggest cleaning as the first step as an affordable trial-and-error option.
Is It Safe to Clean a Flame Sensor Yourself?
It’s technically safe to clean a flame sensor yourself, but you should approach with caution. Any DIY repairs come with the potential to damage your furnace or void your warranty. Only clean the flame sensor if you’re comfortable with it and have some basic HVAC knowledge. It’s also important to shut off the power and gas to your furnace before you begin any cleaning.
Why Your Furnace Keeps Shutting Off – Is the Flame Sensor Really the Problem?
Flame sensors are just one of the issues that can cause your furnace to keep turning on and off. Clogged or dirty air filters are one of the most common causes of furnace problems, and can even increase the risk of flame sensor failure. Learn more about why your furnace is blowing cold air to discover potential furnace issues that can impact your home.
How Cozy Home Services Diagnoses Flame Sensor and Ignition Issues
When we arrive at your home, we’ll get straight to work performing a detailed inspection of your furnace. Professional HVAC technicians use a multimeter to test how well your flame sensor is functioning, and we’ll also do a visual inspection to check for soot and other contaminants. If these tests come back clear, we may take a closer look at other ignition components, air filters, and wiring to diagnose the furnace ignition problems.
Financing Options for Furnace Repair or Replacement
At Cozy, we believe dependable home services should be accessible to everyone. That’s why we’ve partnered with GoodLeap to offer flexible financing solutions for furnace repair, replacement, and more.
Service Area – Furnace Repair Near You
Discover why local homeowners count on Cozy and explore our service area around Vacaville to find professional furnace repair near you:
- Walnut Creek – 94597, 94598
- Concord – 94518, 94520
- Pleasant Hill – 94523
- Lafayette – 94549
- Sacramento (Folsom) – 95630
Call Cozy Home Services for Furnace Flame Sensor Repair
Worried about flame sensor failure? Cozy Home Services is your go-to solution for professional HVAC repairs in the greater Vacaville area. Discover professional expertise, great customer service, and flexible financing from our team of knowledgeable pros. Contact us and get your furnace flame sensor up and running today.
Frequently Asked Questions
Why won’t my furnace stay lit?
There are a number of issues that can prevent a furnace from staying lit, including flame sensor failure, dirty air filters, and broken mechanical components. A professional HVAC technician can diagnose the issue and recommend repair or replacement solutions.
How do you prevent flame sensor failure?
The best way to protect your flame sensor is to practice a regular maintenance checklist. Check your air filters monthly and replace them every three months, or as recommended by the manufacturer. Try to book professional furnace maintenance every year to prevent general wear and tear.
Does a flame sensor failure mean my furnace is unsafe?
Yes, without a flame sensor your furnace runs the risk of releasing dangerous gasses. Most modern furnaces won’t run without a proper flame sensor, so your furnace will most likely shut down instead of operating with a safety risk.
