I've got a '07 JKU, bought it at launch, and it's been great. 160k or so miles (since it has 33's, it's probably higher). So, I've had the check engine on for a few years now for a 420 code for cat's/O2 sensor. My mechanic has basically said it's not to a point that it's an issue yet, and to just watch for a drop in acceleration/gas mileage, etc. None of which I've had.

So, last week the gascap warning came up. I checked my gascap, it's tight, no issues there. It persisted for about a week (I don't drive a ton, maybe 10 miles a day). The other day, however, it cranked up normal, then would basically lose power and turn off. This happened 2 or 3 times, crank, run at roughly 900-1100 RPM's, then shut down.

I like it rest for a second and cranked up again and gave it a little gas to keep it from stalling out, it worked, I put it in gear and drove roughly 7 miles home. Today, it cranked up no problem, drove to the gas station and filled up with 93.

Any ideas? I checked hoses, etc. It's going to my mechanic (friend of a friend tomorrow).

 

I just got the gas cap small leak P0456 check engine light. There's a thread here with a lot of info in regards to potential fixes.
https://www.jk-forum.com/forums/stoc...237480/page10/

The most likely fixes are that you need to either replace the gas cap (Mopar 52030387AA) or the Evap System Integrity Module Detector (Mopar 4861962AA). Even if you have the gas cap tightened it could be the seal around the cap causing problems where some have cleaned the seal and others have just replaced the cap instead. My gas cap is tightened as well and I'm still getting the code. I'm going to just go ahead and get a new cap and a new ESIM Detector to see if that fixes my problem, if not then it's time to start looking for leaks in the vacuum hoses. I have 170K on my 2009, so similar mileage as yourself and likely the same problem.

 

Update to this thread - checked codes, and it is the small leak. New gascap, no luck, looked for kinks in the line, didn't find any, Evap system next.

On another note - I was having issues where the Jeep would shutdown 3 seconds after starting up, I thought this was possibly linked to the gascap warning, but it was very intermittent. I ran the codes today, and got a 513 - Invalid Skim Key, now, I only have one key (the keyfob) that I use. I got a replacement battery (because I'm fairly certain it's never been replaced as I don't really use the locks).

Would a dead key battery cause the computer to sense this issue? I guess I should have ran the codes afterwards to verify.