My furnace has a intermmitent problem. When it quits the fault code is open limit. They all are closed. I can get it to work by moving the wires at the control board connector. The connections appear to be OK. I looked at the rear of the board and did not see any bad solder joints or cracks. Hate to by a new contol board if that is not the problem. Any suggestions?

Intermittents are a pain. Carefully examine the wires. If you find a very flexible place, the conductor inside the insulation may be broken. Cut back to solid wire, and the problem may be fixed.

If the main limit opens too long or often this will happen. What is the temperature rise when the heat is on?