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Z28jeep 03-26-2012 07:12 AM

Check Gas Cap
Wife drove the Jeep yesterday, as she was driving a check gas cap message came up. I didnt check gas cap until this morning and it seamed tight so I took it off inspected it and looked fine. re installed cap and now I have a check engine light along with the check gas cap message. Not sure if its evap canister or a hose or what. Not sure if there is a common problem to look for. Any ideas? thanks

dr.lee.baugh 03-26-2012 09:29 AM

Re: Check Gas Cap
I would first clear all the codes (either with a scan tool or removing the negative battery terminal for 20min) to know where you are starting from.

As you have done, make sure the cap is tight, and then see if the code/message returns.

If it does, pull the codes (though it is likely P0457 and/or P0456) to verify that's what is tripping the CEL.

If there is still a problem, I would start with the simple and cheap solution - get an OEM gas cap. Visually expecting the gas cap may not reveal a failure in the seal. Clear the codes and try again. If it still returns, then I would check the evap canister and vacuum lines running to it (under the bumper on the side of the fuel filler). If there is a leak, you will likely be able to smell it if you stick your head under there.

If everything in the back looks alright, another possible cause is the EVAP purge solenoid located under the hood (drivers side, attached to a fuse box). Another simple/cheap thing to fix.

If all that fails (which I doubt, it is likely one of those), I'm out of ideas!

Good luck.

SvenskaJeepGuy 03-26-2012 11:41 AM

Re: Check Gas Cap
replacing the gas cap is a cheap fix to try

Z28jeep 03-26-2012 02:37 PM

Re: Check Gas Cap
I checked it all and everything seems fine. I will clear the code and see what happens in the next couple days I guess.

kennzz05 03-28-2012 10:31 PM

Re: Check Gas Cap
had this happen on my srt i did nothing and it went away on its own after awhile. have read about being careful not to top off the tank when refueling as the evap hose is right there in the fill tube and getting liquid fuel in that tube can trip the light

clearing the code did nothing it came right back. time and numerous start, stops is what made mine go away

2005JGC 03-28-2012 10:35 PM

Re: Check Gas Cap
The ESIM (evaporitave system integrity monitor) switch that is mounted on the charcoal canister, this is the switch that basically deturmines the leak severity (in few words). This is common to stick and suggest a leak when there is no leak at all.

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