There is a flame rod inserted into your burner. I want you to clean this and retry furnace. Clean with sand paper or steel wool. If it locks out. I want you to look thru hole in blower door and check diagnostic light. Count flashes and check diagnostic chart for problem. Get back toe. Rus
I am a Trane dealer and I have experanced a problem with the flame sensor because of poor grounding. Check all grounding wires including the one that is on the burner tubes. If any grounding problems then the sensor will not detect the flame properly. If all grounding wires appear ok. Try replacing the flame sensor. Its an inexpensive part and its worth a shot.