Originally Posted by kurt h
a very common problem with the flame rod (sensor) is that over time a thin layer of carbon will build up on rod and send a false signal to the ignition module causing it to lock out.usually you can pull it out and carefully sand the flame rod.reinstall. Make sure you have a good connection to board. And a good ground to furnace where rod holder is attached.
on my unit i have aux limit and high limit switch cant seem to find them i checked roll out switch ok i just changed flame sensor i have been adjusting white rodgers pressure on gas it seems to help it sounded like a jet airplane taking off i would like to try and check high limit switch if i could find it and how to check it i would also like to say thank all of u for helping with this problem this site is the best