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Problem: Furnace locks out occasionally. I have to reset the power switch before it will start up again.

Problem: I purchased a flame sensor from you hoping this would solve my furnace lock-out problem. My furnace still locks out occasionally. I have to reset the power switch before it will start up again.

Answer: Thanks so much for your business! I am sorry to hear that you are still having problems. I try to help people out by giving them the easiest and least expensive solutions to their problems that I have seen over the years in my HVAC business. Most of the time a furnace will lock out because the flame sensor needs cleaning or replacing. We sell many different furnace flame sensors on the following page: Please click here to see the furnace flame sensors we sell.  Sometimes other components, parts can cause problems. Sounds like you have an occasional problem that is going to be hard to find because the problem only occurs sometime. You almost have to be there when the problem occurs with a meter to test and find out what the problem is. Many times the furnace control board will give you a flash code telling what the problem might be. I would suggest if your furnace is equipped with a control board that has a flash code that you read the code the next time the problem occurs. This problem could be a safety control problem (pressure switch, limit switch) or a control board problem.  Below we have a real good furnace troubleshooting youtube video that was made by Jreshow which shows seven tricks for repairing your furnace. Many thanks Jreshow! We also have a real good Youtube video made by Acservicetech that shows how to test a furnace flame sensor and how furnace flame rectification works. Thanks so very much to Acservicetech for making this great troubleshooting video! Best of luck in finding your furnace problem. If you have any other questions please email us at: or comment below. We would love to help you troubleshoot and repair your furnace!

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