Technician found that furnace was displaying an open high limit code on the control board. However, all high limit switches tested closed. Technician then unplug and replug in the 12 pin connector on the control board and the code went away, and the furnace began operating normally. Potentially a poor connection in the 12 pin connector or an issue with the connector on the actual mortise self is causing this issue. If the issue continues, replacing the control board would be recommended.