2012 Error P13D6

I have an error that i can clear and only comes back on days it really wet out. It seems like the car is running fine but the code P13D6 will come up saying glow plug on cylinder 3. I can clear the code and weeks will go by then on another rainy day it returns. My question would be is this a symptom to a different problem? Also could it be the glow plug harness?

Thanks

Generally if it's the harness it will affect more than one glow plug, but not always. I would check the resistance on the glow plug, this should tell you if the glow plug is the problem. I do not know what it should be, but you can test a couple of the other glow plugs to make sure #3 is close.