CEL for "small emission leak"

[deathbypsi]

Im new to working on KJ's and my girls 03 keeps bringing up a code for " small emissions leak" and I was wondering if there was a known problem or area to look at before I go ripping into her truck. I did a visual check under the hood and found no bad lines or hoses so Im guessing its something under or in the rear of the truck to do with the fuel tank vapor system.

Any advice on where to look?

 

[Corwyyn]

Got a specific code (Pxxxx ?) Could be something simple like the fuel filler cap, a bit more specific info might help trace it down.

 

[deathbypsi]

Not the cap for sure....always the 1st thing I check. I will run the codes agian tomorrow and post it up.

 

[Dave]

Agree with Corwyyn. First thing to check is the gas cap.

Cycle the ignition key or put a code reader on it.

To get the code by cycling the key do this.......turn key to on position....then off.....then on ....then off....and then on and the code will appear in the lower center of the instrument cluster. You need to do this within 5 seconds. Note that "on" is not start and "off" is not all the way off. You might have to try it a couple of times to do it right. It works on 02-05 models for sure. Mine does it. Took me a couple of times to get it right. Hope I am explaining it right.

Dave

 

[deathbypsi]

OK, to be clear.... I have checked the gas cap already and it is fine. The gas cap is the first thing I check with a CEL. I have been a mechanic 25 years {ford}so I pretty much have the basics covered I also own a very nice OBD2 scanner so getting the code again is not a problem,just need to wait for her to get home from work with the truck.

I was just wondering if the was a problem with maybe a certain hose that leaks after a few years,or rubber line that falls apart with age, etc.....I figured there may be a common problem that people before me have delt with and was just lookin for some ideas before I dig into it to deep.

 

[ohaness]

I found 3 leaks (cracked hose) in my system. I also replaced the cap to be sure...Two were found (one was large, the second questionable) attached to the test port (green cap) near the purge solenoid. When the code reappeared, I replaced the cap. Still did not help. Finally crawled underneath and inspected the fuel tank, evap. canister, fuel filler neck area as best I could. Finally found a crack in a hose from the evap canister to one of the lines going to the purge valve. I was lucky. Did not need to go through the smoke, etc or just replacing parts.

 

[Dave]

The purge celenoid is next to the battery (at least in my 05 but probably the same as your 03) Trace the lines checking them all the way to the rear. The vapor canister is next to the gas tank on the drivers side. Sounds like there could be a small crack in one of the lines then, from your description.

Dave

 

[deathbypsi]

Thanx guys! Thats what I was lookin for.

 

[The Fixer]

On my wife's '03KJ, we had a "small leak detected" code also. I did some searching under the truck and found a dry and cracked rubber hose going from the canister to the fuel tank. Replaced it last year and the code hasn't been back. Hope that helps!

 

[67Customs]

Mine just had a P0456 a couple of days ago. I took my locking Mopar gas cap off, cleaned it and tightened it back on. I noticed that the seal looked a little worn and flatter, but tried it anyway. Nothing. So, I decided to replace it with the stock one yesterday. The light went off on the way back home this evening.

Guess I will go buy a new locking cap.

Anyone know a good one to get? I have only had the Mopar one for a couple of years.

 

[ThunderbirdJunkie]

Just out of curiosity, what did you do to rule out the gas cap?
Have you checked out the evap lines by the tank?

 

[deathbypsi]

I havent had time to look at the truck further yet but I should on sunday. The cap you can see has a good rubber seal and you can see where it is sealing against the filler neck. I am betting on a hose under the truck like others have found......

 

[deathbypsi]

Well, turns out I found the leak today when I was installing a lift on the truck.

Under the battery tray attached to one of the strut bolts is a vent tube line.This line was split open about three inches. I repaired it and finished the lift earlier today and so far no more engine light.

 

[ThunderbirdJunkie]

That's not a vacuum line, it's a vent tube for the front diff. It is not a part of the evap system

 

[deathbypsi]

That's not a vacuum line, it's a vent tube for the front diff. It is not a part of the evap system

Oh reeeaaallllyy?? well thats great news. lol! Here I thought I fixed the darn thing! I guess I will see how long that light stays off then.

 

[JeepJeepster]

Purdy sure there is a vacuum line in that area also. Run back by the headers and under the jeep somewhere. Its a hard plastic line though.

There are some hoses just in front of the gas tank that will dry rot and crack causing that error code.

 

[ThunderbirdJunkie]

Oh reeeaaallllyy?? well thats great news. lol! Here I thought I fixed the darn thing! I guess I will see how long that light stays off then.

Sorry, figured you should know now rather than 2 days from now when the evap system pressurizes itself and throws the same code causing you to rage

 

[JeepKj03]

I had two evap lines that run buy the battery and go down by the fire wall on the driver’s side to replace. I had to replace the rubber lines because they had cracked by the connections. It takes about a foot and a few inches to replace the two rubber hoses. Since it is a small leak it is only a hole between 2-7 thousands big before it becomes a large leak. Hose is cheap if you can get to it easy replacing it and see if that solve the problem. If you still have access to an OBD II scanner that is able to do a garage evap leak down test that should help to see if you pass or fall without having to wait for a code to set again.

 

[2003renegade]

ya check by the gas tank. it happened to me a couple months back. fixed the problem.