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More Codes


NAXJA Forum User
Ok, I've looked at the other threads on codes, but no one seems to be able to answer the question that I have. I got tired of that check engine light and with multiple vehicles and autozone no longer running codes, I bought a scanner. I have two codes, the first being P0455 Mod$D1 EVAP Emission Control System Leak (Large) and the second being P0442% Mod$D1 EVAP Emission Control System Leak (Small). Now my question is, what in the hell does all that mean? Ok, I have a leak, but how do I narrow it down to an area a little more specific than "Your Jeep"? Also, a bunch of guys say to check the gas cap. Done that, not it. Cap doesn't leak and it's tight. Anyone have any experience with these codes or have had them in the past? What was wrong with your jeep? Where did you find the leak? I just need some help with these codes and I'm just not sure where to start, so any help would be great, thanks.
I had the same problem on my 87. No OBDII on that, just wouldn't pass emissions for an evap leak.
There are some vent lines that come off the top of the tank that can get nasty and leak. There are also some lines in the engine compartment that are the same thing. Those are both easy/cheap to check and replace.
Other than that you may have to inspect the tank and look for a hole. I had a small hole on the top of the tank. Also not a big deal to fix.

Happy Trails,
87 XJ
00 Xj
My second gas cap stopped me from getting po455. The code generaly came within a day after filling tank. I also try never to over fill tank. I have 2000 xj
yeah, i'll try that. i always have the bad habit of trying to go to the next dollar when i fill up. i guess i'm going looking for lines today, huh? i'll write back and let you know what i find.
yup.....to all those who said gas cap. i spent 18 dollars from the dealer getting a stock gas cap, popped it on, erased my codes and have been driving it since then with no problems. so far i've driven over 600 miles since the fix and multiple fillups and the code hasnt come back. thanks a bunch guys.