A furnace depends on a small part called the flame sensor. This part keeps your home safe. It tells the furnace control board that a flame is present and that the burners are working. If the sensor cannot read the flame, the furnace will shut off to protect your home. Many homeowners in the Dallas area run into this problem during fall and winter.
What a Flame Sensor Does
A flame sensor is a thin metal rod that sits near the burner. When the burners light, the sensor picks up a tiny electrical signal. This signal confirms that the flame is real. If the sensor does not pick up that signal, the furnace will turn off after a few seconds. This prevents the system from letting gas flow without a flame.
Signs of a Dirty or Faulty Flame Sensor
A dirty sensor will cause the furnace to act in ways that feel random. These signs are common:
- The furnace lights and shuts down almost right away.
- The system tries to start more than once.
- You reset the furnace often.
- The furnace short cycles, turning on and off quickly.
- The sensor has soot or corrosion on the metal rod.
These problems get worse during long off-seasons when dust collects inside the furnace cabinet.
Why Flame Sensors Get Dirty
Flame sensors often get covered in dust. Furnaces in the Dallas area sit for most of the year. Dust blows into the attic. Moisture from small air leaks can cause rust. Older systems may build up residue from years of heating. All of this blocks the signal the sensor needs to send to the control board.
Can Homeowners Clean a Flame Sensor
Some homeowners try to clean the sensor themselves. A small mistake can cause bigger problems. The porcelain on the sensor can crack. The rod can bend. A scratched sensor will stop working. Reinstalling the sensor in the wrong spot can lead to more shutdowns. A technician can clean or replace the sensor safely. A trained technician also checks the burners, wiring, and control board.
When To Call an HVAC Technician
Call a technician if:
- The furnace shuts off over and over.
- The sensor looks rusty.
- The sensor has cracks or heat damage.
- The furnace is ten years old or more.
- Cleaning the sensor did not help.
- The system locks out and will not run.
A technician can test the flame sensor with the proper tools. This helps prevent damage to other parts.
How To Prevent Future Flame Sensor Problems
You can avoid most sensor problems with simple steps. Replace air filters on time. Keep the furnace area clean. Seal attic gaps that blow dust onto the equipment. Schedule a yearly furnace tune-up before cold weather arrives. A tune-up includes cleaning the flame sensor and checking the burners. This helps the furnace run longer and use less energy.
Typical Costs for Flame Sensor Cleaning or Replacement
Most Dallas homeowners spend:
- $89 to $150 for cleaning during a tune-up.
- $150 to $300 for replacement, depending on the furnace model.
A sensor fix is usually fast and keeps the furnace from shutting down again.
Why Fixing a Dirty Flame Sensor Matters and When To Call Bolton Heating & Air
A clean flame sensor helps your furnace stay on and heat your home without shutting down. It keeps your system safe and reduces how often the furnace tries and fails to start. It also helps lower stress on the burners and control board. A small repair can prevent bigger problems during cold weather.
If your furnace shuts off after a few seconds or keeps short cycling, your flame sensor may be the cause. Bolton Heating & Air can test the sensor, clean it, or replace it if needed. Our technicians work on all furnace brands and serve the entire Dallas and DFW area. If you want fast, clear answers and safe repairs, contact Bolton Heating & Air and schedule your furnace service today.