My furnace will stay lit for somewhere between 30 minutes and a couple hours but then will shut off and show a lockout code. Should I clean the flame sensor?


While it doesn't hurt to try cleaning the sensor, I'm not sure that's your issue. Usually a unit fails, for whatever reason, 3 times before it locks out so I would try and see what's happening prior to that. That might give you a better idea of where in the cycle the breakdown is occurring.

Updated on January 8, 2018

Original Article:

Troubleshooting Common Furnace Problems With an HVAC Expert
By Dan Robbins