I have been chasing this code relentlessly since I bought this Jeep back in November. I thought I had it fixed. I had no check engine light for probobly two months but the other day I got the light again.

So today I decided to go to the junkyard and get almost a whole new evap system.

I got a new LDP, all rubber elbows in the evap system, all lines across engine bay and back to the rear.

My system was bad before I got it and it looks like someone was chasing it for a while. there was all sorts of rigged up elbows and adapters in the back instead of the factory pieces. They are all back to factory.

I also replaced my fuel filler neck. When I thought I beat it before I had the tank dropped and there was some corrosion between the filler hose and neck. I removed the corrosion which resulted in some pin holes in the filler neck so I had to move the hose/clamp high up the neck. When the tank was dropped everything up top there and the gasket were checked and double checked. They are good.

in addition to the filler neck I also grabbed another gas cap.

So....

All new lines, all new elbows, new LDP, new filler neck, new gas cap
previously checked tank pieces very well so I guess if the light returns the only thing it could be is the charcoal box.

we'll see!

 

I'm no help, except to commiserate and bump your thread. Bummer. Sounds like a *****.

I think almost every time I've found pinholes, and corrosion, (on anything), I lost that one. It seems I always missed one, or there there is another tomorrow.

 

smoke test system...

 

Yeah, I'm in the same boat dude. I got a rich scent of fuel on start-up the other day. That's the first time that ever happened. It sat in the garage all weekend and gave me the CEL upon starting-up this morning. A quick connection to the code reader and voila! There it is again - the dreaded P0455. I guess it's my turn to crawl all over the purge system...

 

Find a donor in the junk yard and pull the whole system. It's easy. No tools required.

 

Maybe check / replace the charcoal canister? Also, try building your own smoke tester using household items. Here is a link to the one I made. I used an old air pump, went to the local bike shop and they gave me a valve stem off a blown innertube, some incense, and some rubber tubing.