Goodman gmp125-5 Blows constantly but no heat. No flame. Just blows.

You probably already figured this out, however, more then likely it is the circuit board. It cost aprox $91 (taxes not included) its relativly simple to replace. I had the same issue and that did it for me. Make sure you mark all your connections before removing them and maybe even take a few pictures in case. Good luck!

There is a Primary High Limit Switch towards the middle of the furnace, it more than likely needs to be replaced, very common to go out only after a few seasons. Also, you could have a flam rollout switch tripped that will signal the same code, these switches are re-settable and are located on the outer top and sides of the burner assembly, they’re about ½ inch in diameter with a red push button in the center and two wires “ usually purple” coming off of them. If either of these are tripped or bad, the blower will stay on indefinitely.

Hope this helps