Tip & How-To about Heating & Cooling

Gas Furnace Lights for 5 seconds and shuts off - it will do this 3 times

If the burners of your furnace light and go out after approximately 5 seconds, the problem is most likely with the Flame Sensor. The Flame Sensor will develop a light coating that will prevent it from sending a "proof" signal back to the main board. If the main board does not receive this "proof" signal, it will shut off the gas valve. After 3 attempts, it will lock out leaving only the draft inducer motor running. Here is a video demonstrating how to identify and clean the flame sensor to get your furnace back to running normally in only a few minutes.


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furnace lights and works for 5 or 10 seconds then shuts off


If this is a residential furnace the problem may be a dirty or defective flame sensor. It may also be from the burners not lighting all the way across. This is usually caused from blocked crossovers on the burners. Remove and clean the flame sensor with steel wool or sandpaper.Reinstall and see if that corrects the problem also check to see that alll burners are lighting correctly. If they are not contact a service proffesional to have the burners cleaned or replaced. Hope this helps.

Dec 12, 2013 | Heating & Cooling

1 Answer

Thermostat calls for heat, purge motor turns on, 15 seconds later hot igniter turns on, then gas turns on and burners are lit. Problem is, they only stay lit for 5 seconds then shut off and cycle repeats over and over. Is it the flame sensor?


,Hello, Make sure the flame sensor is clean near the burners, The flame sensor is a metal rod that is on the opposite side of the ignitor. To clean the flame sensor you will need some steel wool, turn off power to the furnace and remove the flame sensor and clean it with the steel wool. After cleaning reinstall it and turn power back on to furnace.

Mar 02, 2011 | Goodman Heating & Cooling

1 Answer

Goodman Model C16-28 1FF is not able to heat my basement. The burners igniting but only fire for approximately 5 seconds. This cycle continues about every 60 seconds. At times the burners only stay on for a second or two


Sounds as though your issue lies within the flame sensor.

The flame sensor senses that there is flame present once there is a call for heat. It sends its signal back the board or ICM and the furnace operates as normal. If no signal is sent, then the furnace automatically shuts down as a safety procedure. The furnace will attempt to light several times before shutting down on a fault code or lockout.


The number 1 reason for flame sensors to fail is they are dirty. Check the sensor for dirt build-up. Clean the sensor with a damp rag or a scratch pad. Inspect the grommets for crackings. Also check and clean all grounds. If this doesn't work, you will need to replace the sensor or call for a service technician to ensure the sensor is the only issue at hand.

Jan 08, 2010 | Goodman Heating & Cooling

1 Answer

Goodman furnace seems to be cycling too often. Burner not staying on long enough to put warm air into system. Burner quits after a few seconds then repeats.


dIf the burners are only staying on for about 5 seconds, you proably hav e a dirty flame sensor. Watch the burners light, the glow plug will light one end of the burners, in front of the last burner to light the will be a small thin rod, this rod must sense the flame or the gas will be shut down. Take a piece of steel wool and gently cleqan the rod.

Oct 11, 2009 | Goodman GDS80904BNA Open Flame Heater

1 Answer

heater lights for about 5 sec and then goes out


One flash on a Ruud furnace indicates failure to ignite. There is a viewing port on the furnace where you can watch the flame. If the ignitor is igniting the burner and then 2 or 3 seconds later, the flame goes out; you most likely have a flame sensor that is dirty or not working. Check to make sure you are getting gas. Check the connections of all wires to the control board. If the sensor is not part of the ignitor, see if you can get to it to clean it with a small wire brush. Make sure there is a good ground connection between the board and furnace frame. If the flame is not traveling all the way to the flame sensor, clean your burners. If the flame burns inside the burners, you may have weak gas pressure. Good Luck.

Sep 29, 2007 | Heating & Cooling

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