Newbie here (first post). Proud owner of a '10 Rubicon Unlimited (my third Jeep). Check engine light came on during the test drive. The dealer was very transparent and we took it to the auto shop and they ran a diagnostic. P0456 small leak/dreaded EVAC issue. I spent the last two weeks watching videos and reading forums. I decided to change the EVAP module & gasket as that seems to be a common problem. I checked the integrity of all hoses including rollover valve hose and hose to the EVAP module. I checked to canister for cracks, and the integrity of the gas cap and made sure it was shut and the gasket was good. I cleared the code after installing the new evap module and the light came on after driving 10 miles. I took it back to the dealer since I'm in my 90 day warranty window and they called me back today saying it's fixed. I was told the problem was excess carbon build up in the fuel tank. I am not too mechanically savvy but I know carbon build up can occur on intake valves, but I don't know much about carbon in a gas tank. Is this carbon in a solid or gas form? In all my research I didn't here anyone mention carbon build up as a cause of the P0455/56/57 codes. I just want to make sure the dealership isn't trying to shoo me away. Thanks for the help.

 

Never heard of Carbon in the gas tank; overfilling when gassing up can contaminate the carbon in the canister and cause pressure issues thus an EVAP code. I would be asking for more detailed info and how they think the Carbon got into the gas tank.

 

Jay2013- Can you elaborate on how overfilling can cause carbon build up in the canister? Also, how does one remove the carbon to make the light go out?

 

OH should have used Charcoal...Lets look at this possibility: Gasoline overflows into the vent tube and trickles into the Charcoal Canister. Remember that once you start pumping fuel into the neck, you’re overflowing into the vent tube now that the fluid level is higher than it. Once the gasoline reaches the canister, it mucks up the entire thing so that it no longer is able to properly collect and then purge excess fuel vapors into the intake manifold when the car starts up. Ruining the Carbon Canister doesn’t come immediately. There are lots of ups and downs in the vent tube, and it takes some time to screw up that canister. Like you I never heard of CARBON in a gas tank; thus the thought of shop using incorrect terminology.

 

I too have not heard of this issue. If they are fixing it, continue to drive it to see if it comes back. Did they replace the charcoal canister this last time?
I had an issue with the vent tube breaking at the connection to the tank after I replaced the fill tube with a newer externally located check valve fill tube. I fixed the broken connection

 

I've never heard of it going back into the charcoal canister. My guess is that the integrity module gasket wasn't seated properly and they did the job over and the code went away. That or the small code could come back now in about 100 miles or so. You will know soon enough. If that o-ring on the module isn't perfect you will throw the code. I had to get mine smoke tested to see how the washer wasn't seating properly.

The module and canister are both under $75. You can also try installing a new Purge Valve for $20 if you wanna play the parts roulette game should the code come back or at least check the hoses by the purge valve since they can sometimes rub heavy on the battery.

 

UPDATE- Picked up Jeep from dealership with the light out......light came back on after 20 minutes of driving. Very disappointed. According to FL lemon law the dealership has three chances to fix the issue, and then I have the right to take it to the dealership. I hope I don't have to go that route, but I've been burned before so I'm documenting all this. Next step is to talk to the mechanic that did the work so I can get a better feel for what was done. I don't know for sure if they did a smoke check or not. The didn't replace the vapor canister, they said they "cleaned out the carbon." Is that possible, or is it a closed system?

 

Welcome to the forum. You might want to recheck that lemon law, FL lemon law applies only to new vehicles. Keep working with the dealer and document it incase you need it for small claims court..

 

Sounds like a bullshit fix from the selling dealer. You need the right to take it to another dealer for diagnosis.