I have a lennox uhg2-75a-3 furnace. When the furnace starts up only the blower motor will run, the furnace acts like it wants to kick on but the inducer motor shuts down about 5 seconds after. The blower motor will continue to run through this whole process and will never shut down. What's interesting is when I remove the plug from the pressure switch to the high limit switch and plug it back in the whole furnace will fire up normally. Once the house reaches the desired temperature the flames shut down once again but the blower will continue to run. The furnace will not ignite on its own until I unplug and plug that wire in again. I had a tech come out the other day and he couldn't find a problem he said the wiring was correct and the correct voltage was present throughout the whole system. His only conclusion was that I have a bad board, I just wanted to a second opinion before I purchase a new board. Any insight on this?

A technician on site with tools is going to give more help than us. However. h should be able to test that board and not just guess