Arrived and cchecked gas line found gas valve was turned off, turned on watch unit cycle, did not try to light, i cracked gas line to be sure that there was gas coming through and not air, smelled gas, I checked igniter, I watched unit cycle again through code that pressure switch was stuck, I cleared tube and discovered common wire going to pressure switch became unplugged somehow, i plugged it back in watched unit cycle and it did light furnace operating as it should.