P0456 Evaporative Emissions System - Small leak detected

Well I had my first trouble code come up at 149k miles. I started my truck as usual after work and the check engine light was on. The truck ran smoothly no hiccups the whole 40 miles home.

I checked the code and this is what came up: P0456 Evaporative Emissions System - Small leak detected

I erased the code and I will see if it comes back or not.

It has been raining heavy here the past few days, not sure if that might have anything to do with it. I changed the exhaust gaskets over the weekend. I just added, maybe, 4 oz of coolant to the reservoir.

I am not sure if any of the above has anything to do with it, we shall see. All of my research indicates that this is usually the result of a improperly sealed gas cap. I took it off and put it back on. Also when the truck is idling I thought I might have heard a hissing sound coming from under the engine, like a vacuum hose, not sure though. I will look into it tomorrow, not too worried about it though.

Anyone have this code before, any thoughts?

 

Check out that hissing, if all is good just wait and see if light comes back. If it does go get a new gas cap from dealer and try that.