System works fine oyher than fan running when it wants to

Take the cover off the burner compartment of the furnace. Obtain the make and model of the furnace off the rating plate in the burner compartment and post it here.

Observe the sequence of events that occurs at the furnace when you turn up the thermostat and post that sequence of events in order and in detail.

Also, look for a sticker that deswcribes what the diagnostic codes indicate. Often it's on the inside of the fan compartment door.

What you've posted is too vague to be of help.

Goodman gmp125-4 false flame

Your replies are WAY TOO VAGUE to be of any help to you.

You must follow the following directions if you want some help:

Observe the sequence of events that occurs at the furnace when you turn up the thermostat and post that sequence of events in order and in detail.

Also, the Goodman GMP furnace manual does not list any diagnostic codes.

"false flame" is too vague to help identify what might be happening with any confidence.

Is there any additional information given with this code? If so, post it.