Goodman Heater runs and shuts off periodically.. Pilot lights and burns for 5 seconds and shuts off. Blower runs, pilot lights and burns for 5 seconds and shuts off.. Cycle repeats 3 or 4 times and then furnace shuts off. I then have to pull fuse and replace and process starts again. After 2 or 3 run throughs, it will then run fine for 2 to 3 weeks.

Clean the thermocouple.