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Discussion Starter #1
Hey all,

I've been messing around with this problem since I bought my Jeep, it keeps throwing the P0456 code (small evap system leak). I've replaced the gas cap twice, I tightened the hose clamp around the main gas tube where it connects to the rubber hose, I noticed there is also a smaller one that shoots off of it and am planning on replacing that clamp since it won't tighten anymore. Sometimes I can smell gas around the cap area.

Are there other trouble spots I should be aware of when it comes to this code? It's starting to get a little frustrating tracking this thing down.

Thanks!
 

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Disconnect a vacuum line and blow some smoke into the intake manifold. See where it comes out.

Also, keep in mind, an internal leak in the brake booster can mask a leak in there.

YouTube is your friend too.

Good luck.
 

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Ive been struggling with this same code for a month or so now. I replaced the gas cap, smoke tested everything and found no leaks. I spoke with someone he didnt give me much detail but said it might be a bad solenoid. Planning to try and chase that down this weekend if I get the time. If you figure it out let me know
 

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Discussion Starter #4
Ive been struggling with this same code for a month or so now. I replaced the gas cap, smoke tested everything and found no leaks. I spoke with someone he didnt give me much detail but said it might be a bad solenoid. Planning to try and chase that down this weekend if I get the time. If you figure it out let me know
Will do! Let me know how it goes.
 

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My two cents: If you occasionally smell fuel it's likely that you have a small crack in a hose. There are a few rubber hoses that run from the engine bay to the gas tank that will rot over time. It can be so small that the fuel wont drip out because it evaporates before it hits the ground. Or it could be leaking at certain connections on top of the fuel tank. Which would require you to drop the tank to inspect it. Or you might need to replace the filler hose.
 

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What year & model is your Jeep?

Evap systems will vary by year & model.

I had p0455, p0456, & p0457 codes for the longest time until I pulled the passenger rear inner fender to mount a shock reservoir. That's where I found the Evap Canister and the Evap Leak Detection Assembly. One of the Vapor Lines had a huge crack in it.
 

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I have some codes popped. I keep my fingers crossed every smog inspection.
If I reset the ECM, and drive straight to the shop about ten miles away, I will pass, and receive a sticker. A few miles after passing inspection, the Engine Light will pop. Once the light comes on, I will not pass. BUT. If I try to inspect too soon after resetting the codes, I will get a "Not Ready" status and fail.


There is a few mile window between "Not Ready" status and Engine Light activation that the truck will pass. I've done this every year for 6 years since I got the Jeep.



I gave up trying to figure out the emissions problems on the older vehicles. If a car has more than 60 or 80 thousand miles, that damned engine light is always on.
 

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Discussion Starter #9
What year & model is your Jeep?

Evap systems will vary by year & model.

I had p0455, p0456, & p0457 codes for the longest time until I pulled the passenger rear inner fender to mount a shock reservoir. That's where I found the Evap Canister and the Evap Leak Detection Assembly. One of the Vapor Lines had a huge crack in it.
It’s a 2001 SE 2.5L

I will check the passenger side when I get a chance. I tightened all the hoses on the drivers side and replaced a hose clamp on one of them, also removed the retention ring from the new cap I bought and it seems to tighten down better now, I reset the code so we will see if it pops again.

Thanks!
 

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You're using mopar gas caps and not cheap parts store ones?
 

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After trying a few of the above suggestions, I just replaced my fuel vapor line on my TJ in hopes of solving my P0456 error. The line was heavily rusted and looked damp in a few spots near the rear of the Jeep. When I pulled the old line out, the rusty parts were so thin they just broke apart. I'm thinking maybe there were a few pinholes that had rusted all the way through that were causing my problems. Install was easy and only took about 30 minutes with no tools needed. So far, no CEL's!

Part number is 52127601, not sure if it's different for a 2.5
 

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I'm having the same problem. I replaced the gas cap with a mopar cap. Reset the code and drove about 80 miles and the light came back on.

A few months back I had noticed fuel leaked out from under the jeep on the side the gas cap is. That's around the time the engine light went on.



Popped open the plastic under the the gas tank and above the drivers side rear wheel and noticed a hose that was wet and showed signs of leakage.



I removed the zip tie to the hose and It seems that fuel came out of this hose with a plastic tip on it. The plastic tip is loose and swivels around. It seems fuel leaked out of this tip and caused a mess.
Anyone know what hose this is and what would cause the hose to leak fuel out of the tip?



Thanks in advance!
 

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These codes are very difficult to diagnose typically...I struggled with one for a while last year, replaced gas cap, taped up suspect vacuum lines, etc....all with no luck. Had to take it to a shop where they did a “smoke test”. Found a pinhole leak on the top of the gas tank filler (up near the tank itself). Replacement was about $750 if I remember correctly as it required a whole new tank. About $1 worth of well placed epoxy fixed it...and all is well in the world. (Smoke test cost me about $150-200). It may be worth taking it to a local shop just to see if it turns up anything...
 
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Found the problem with my P0456 CEL. It was the 52059518AB Canister Hose




CEL is off and 200+ miles later it's still off
 
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