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kyfredrickson 07-12-2010 07:46 PM

DTC PO456 and PO457... Check Gas Cap
Ok first off, thank you checking my post to help me out, Im a total newbie. I have a 2005 grand cherokee 4.7L 80k Miles. My check gas cap light is on.

I went to o'reilly to use their code reader 2 possible errors came up.DTC PO456 and PO457, with the check gas cap light on. I know their is a service bulletin about this but im lost. I bought a new gas cap last week and cleared the code, but it still read check gas cap so i unplugged battery and that solved that problem, but 2 days later it came back on.

I just got back from o'reilly again where they gave me a free gas cap again to try it because they insist that must be the problem.

Any thoughts? Iv searched the forums and found some but nothing to helpful. Thanks guys!

Scottina06 07-12-2010 07:51 PM

Re: DTC PO456 and PO457... Check Gas Cap
get an oem cap........

robpp 07-12-2010 07:55 PM

Re: DTC PO456 and PO457... Check Gas Cap
check the canister and the vacuum lines running to it. its under the bumper near where the gas cap is

angelfelon 09-06-2013 05:13 PM

Re: DTC PO456 and PO457... Check Gas Cap
I had bought a locking gas cap from one of the parts stores and the 98 GCL would stall and die right after I put the new locking cap on so make sure you got the correct gas cap . I wonder if some of the people they hire know anything at all about vehicles. Its always better to know what parts are the right parts before you go to parts store.

DAVY27 09-06-2013 05:24 PM

Re: DTC PO456 and PO457... Check Gas Cap
x2 on the oem gas cap. Drive it around a few times and it should disappear.

2005JGC 09-07-2013 10:55 PM

Re: DTC PO456 and PO457... Check Gas Cap
Honestly, I didnt replace many gas caps on WK's... as a matter of fact none ring a bell. A VERY common issue on these systems was the ESIM switch (evap system integrity monitor). It mounts to the canister and the switch inside of this contraption starts giving false info. It uses the switch to know if there is a leak in the system and when it fails it gives false negatives. by far the most common failure on the WK that I have seen.

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