Sealed Fireplace - Won't remain Lit
 

I've got a fireplace in my upstairs bedroom that I rarely use. It is a sealed unit (glass covers the gas logs). I am able to start it and when I press the wall plate switch it does fire up and will burn for about 5 minutes, and then it goes out. I mentioned this to a friend and he thinks it could be a bad thermocouple?

Attached is a picture of the starter. I am a complete noob on attempting to fix this on my own but, I would like to try if it is not too difficult.

Any advise would be appreciated.

umm
 

Check your vent to see if it is plugged, someone may have moved in and the CO sensor will shut the unit down.