so about a week ago the service engine soon light came on, and my first stop was straight to O'Reilly Auto Parts, they did their free diagnostics and came up with P0455, code definition Evaporative Emission System Leak Detected (large leak), No possible causes available, and a whole list of reported fixes, everything from replacing the fuel cap, to vacuum hoses, to MAF, and on and on. Basically the print out they gave me said "It is strongly recommended that you consult with a knowledgeable professional repair facility for proper diagnosis and repair of trouble code issues". I planned on working on it next weekend, and do other normal maintenance as well, but today I went out to get the oil filter, air filter, oil, and a few other things to clean it up and make it look good for tonight, went and got the truck washed really good, then went to the liquor store, and as I was leaving I noticed the engine light wasn't lit up... I had to double check to make sure it didnt burn out, so I turned it back off, then restarted it, and it came on as it should then turned off...

It is a new gas cap, only about 4 months old, but come to think of it, I am thinking that the time I filled up before this happened, I was distracted at the pump as i went to put the cap on, and I know it didnt feel correct when i put it on, but like i said i was really distracted by the "eye candy" that was right behind me. I didn't want to look foolish by taking the cap off & putting it back on, but I suppose next time I should...

with the P0455, is that a common cause (gas cap), i mean I know it can throw codes, but is that code going to show back up if I go back and have the part store scan it again. I hope that is all it was, I am estimating that I drove about 650 miles with the light on, and I know I filled up twice after the light showed up, It doesn't appear that my milage had been affected by the code, as the last 2 fill ups I had 16.97mpg (most recent-yesterday), and 16.84mpg (early this week-monday), truck didn't run rough, or act different in any way

 

With a 455, your chances of it being a gas cap or very low, you have a major leak that can be anywhere between the tank and the engine compartment. Smoke test would be the quickest way to find it.

 

Perfect Mike, sounds like a great excuse to tell my fiance when she sees me with a smoke in my hand. "No hun, I swear its not mine, I'm just holding it for my land rover"