P0456 (M) Evap Leak Monitor Small Leak Detected Leak has been detected in the evaporative system.


Thats the code I got this morning while driving home. Can someone explain what this means to me? How can I fix it? I think we're just going to take it into the stealership tomorrow because its still under warrenty, but i'd like to learn how to do this kind of stuff.

Is it ok to drive (minimally) with this problem?

 

PO456 is a small leak, and 99% of the time it's the gas cap being slightly loose or otherwise having a pinhole leak. Some people have reported that error due to cracked vacuum lines, but I've had it a couple of times and this last time I think I've got it fixed by spraying some WD-40 into the check valve inside the gas cap.

Either way, it won't hurt the truck at all. It's just telling you that there is a very minute leak in the evaporative emissions control system and that a very small amount of gas might be lost due to evaporation.

You can take it to the dealership, but they'll probably charge you $40 to hook it up to a machine to tell you what you already know, and another $15-25 for a new gas cap.

 

What I ended up doing was just tightening the gas cap, then disconnected the battery and re-set the code. Drove around all day and the light didn't come back on, so I figure it was just the gas cap loose. If it comes back on il do a better inpsection of the tubes and stuff.

 

If it comes back on, look at your gas cap closely and give it a good spraying with something to make sure there isn't a piece of grit keeping the check valve from seating. I think that was my problem.

 

Great, thanks for the advice. I just read somewhere that the gas cap not being on properly is the #1 cause for engine lights in america. Not sure how true that is, but i could believe it.

If that turns out not to be the problem, where is the next place I should look? I don't know which tubes under the hood i should look at, or which tank it is or anything.

 

I would say that the o2 sensor is the number one check engine code.

 

I only ever got O2 sensor codes in my Impreza with a header and high flow cat. I've had CELs in three different cars, and know countless others, from gas caps. I'd wager he's correct. It's also why the first question when somebody calls a shop should be "did you get gas in the last couple of days?", since it may not show up right away.

 

Come on Horatio, they wouldn't make any money doing it that way!

 

First time I got a CEL one that's what the Subaru dealer asked me... then they told me they'd charge near $40 to hook a code scanner up to tell me what the thing was. So I bought my own. Turns out it was for my Cat, since I had installed the header/cat and it the temp change through the cat was outside of spec.