The code I'm getting is 14 for ignition lockout, will reset in 3 hrs. The furnace tries to ignite 3 or 4 times and then the code trips and shuts the furnace down. I usually just flip the manual switch to get it going again but if I'm not home to pay attention or if we're asleep the house will continue to drop in temp. For example, we went to bed with the house at 71 degrees and woke up at 64 degress about 6 hours later and then manually flipped the switch to get the furnace going. When I do flip the manual switch the furnace has no problem igniting, only when it operates automatically does it seem to have the ignition problem.

Any idea what can be causing the "ignition lockout" and is it potentially an expensive repair or can it be just a sensor that's out of whack or something simple/stupid that I can try on my end?

If the burners light and turn off again in about 5 seconds it is probably a dirty flame sensor. Carrier has made hundreds of furnaces over the years so I don't know where yours would be located. See other flame sensor posts for some more help.

If the burners light and turn off again in about 5 seconds it is probably a dirty flame sensor. Carrier has made hundreds of furnaces over the years so I don't know where yours would be located. See other flame sensor posts for some more help.

That's exactly what they're doing! Thanks for the nudge in the right direction it's greatly appreciated, I'll see if I can find the sensor and clean it off.

A small metal rod in front of one of the burners. Turn furnace off, remove it, usually a 1/4" nut driver required and clean it with some crumpled up aluminum foil.