CEL P0442 & P0455

JeepPilot · **Posted:** Tue Aug 19, 2008 10:39 am

A little over a month ago my CEL came on, and the diagnostic told me it was code P0442 (small evap leak). I made sure my gas cap was on tight and reset the CEL. For the past few weeks, my CEL has remained off. A couple days ago, I made a 450 mile trip, and, as of this morning, my CEL came on again, indicating code P0455 (large evap leak) this time.

During my 450 mile trip, I did not experience any adverse driving. Though my engine was idling at roughly 600rpm (as it always has), my engine seemed to maybe be running a little rougher than usual. I thought I felt a little bit of shaking that I hadn't noticed before. Not sure if that was worth mentioning.

Is it safe to drive around for a little bit with code P0455 before I get it checked out?? :?:

jeepkj02 · **Posted:** Tue Aug 19, 2008 12:28 pm

I also have the same CEL codes and my engine runs a bit ruff sometimes.

JeepPilot · **Posted:** Tue Aug 19, 2008 1:48 pm

Talked to a few people about the problem. One potential fix could be as simple as replacing the gas cap itself. I'm gonna run to a dealership and dish out $20 for a new cap rather than take it in and have full diagnostics run. Hopefully the cheaper solution comes out on top. If not, it'll probably involve replacing some hoses that are dry-rotted and cracked. I know the smoke test is $100. Does anyone have any idea how much it'd cost to replace old hoses??

rescu2000 · **Posted:** Tue Aug 19, 2008 7:44 pm

Before you do anything involving the dealer, crawl under the rear end and lie on your back. Look up in front of the gas tank above the rear diff. there are some hard plastic lines that are connected by rubber sections. These rubber sections split wide open. It cost all of $5 to fix mine AND I bought enough extra hose to relocate the diff breather tube to the gas cap area (for water crossings).
Rescu2000

jeepkj02 · **Posted:** Tue Aug 19, 2008 9:02 pm

Where some safety goggles, because there will be a lot of dried up mud and dirt that will fall into your eyes, not good.

I have found a hose that goes from the evap canister to the leak detection pump that has a split end. I put a hose clamp on it and reset the code. Called the dealer they want $10 for it.

Prospect62 · **Posted:** Wed Aug 20, 2008 12:40 pm

rescu2000 wrote:

Before you do anything involving the dealer, crawl under the rear end and lie on your back. Look up in front of the gas tank above the rear diff. there are some hard plastic lines that are connected by rubber sections. These rubber sections split wide open. It cost all of $5 to fix mine AND I bought enough extra hose to relocate the diff breather tube to the gas cap area (for water crossings).
Rescu2000

It's not the gas cap, it's the above. People always want it to be the gas cap (easy fix), but it rarely is. With these KJ's, it's always those rubber lines in the back by the tank that split. Might as well start there.

JeepPilot · **Posted:** Wed Aug 20, 2008 1:25 pm

Prospect62 and Rescu2000, I took your advice. I got on my back under the fuel tank section of my vehicle. Took a look at the rubber hoses that you guys mentioned and I think I found the problem. Took my camera along so you guys can see what I was looking at.

Significant crack in a rubber hose located near the fuel tank.

Not really sure what this is, but the base of this hose is connected to the rear axel.

...and the base of the above-mentioned hose is clearly no longer in tact.

Where should I go from here? I imagine I can just get replacement rubber hose from my local Autozone, or does someone recommend going to a different store? And lastly, is there anything I should know before disconnecting those hoses to replace them? :?:

Fouros · **Posted:** Wed Aug 20, 2008 7:33 pm

the hose attached to the rear axle is your breather

JeepPilot · **Posted:** Wed Aug 20, 2008 11:16 pm

Is it an issue that my breather is torn like it is?? It wouldn't cause an evap leak, would it??

Fouros · **Posted:** Wed Aug 20, 2008 11:20 pm

i would think an evap leak would have something to do with the fuel system

not your diff breather

JeepPilot · **Posted:** Wed Aug 20, 2008 11:23 pm

ok. i'll replace my diff breather at another time, this evap leak is the bigger problem at hand.

so how does one go about replacing lines in the fuel system??

Guest · **Posted:** Thu Aug 21, 2008 12:44 am

JeepPilot wrote:

Is it an issue that my breather is torn like it is?? It wouldn't cause an evap leak, would it??

No, but your mudrunning has probably caused it to take some water in.

That evap hose that goes near the tank is probably the cause of your issue.

Tell me if this is correct:

rescu2000 · **Posted:** Thu Aug 21, 2008 12:44 am

I personally would replace the breather tube also. It will cost less than $5. If you go through 12" (maybe less) of water and that rear diff sucks some of it in, you will have very expensive problems. You can get the hose at Autozone, Advance, etc. They will probably give you transmission hose. Just be sure to cut that plastice breather out and insert it into the new hose and put a small clamp on the bottom where it connects to the differential.

From the looks of that Breather Tube though, I am betting you still have some other Emissions System hoses up around the gas tank with splits. Look them over pretty carefully and follow them as far as you can.

Rescu2000

Guest · **Posted:** Thu Aug 21, 2008 12:49 am

Just to clarify...I didn't put in the "this one" and "NOT this one" for this purpose...those were there from a different time:P

I was simply trying to get a good idea of the general area of the hoses, since i couldn't really see anything in his pic.

*EDIT*

ok, the first pic of his are the two hoses going into the canister?

rescu2000 · **Posted:** Thu Aug 21, 2008 12:59 am

And Tbird is right with the blue arrow. That small section is the same size as the breather hose and it is the same stuff. I would bet money that it is split. I bought 5' of hose and replaced that short section and had enough left to run the breather tube up to the gas tank area. I drilled a hole in the plastic around the gas cap and my breather is stick out next to my gas cap.

I hope it doesn't suck in gas fumes and turn my rear differential into a bomb... Talk about grenading a diff... (And no I am not serious)

rescu2000 · **Posted:** Thu Aug 21, 2008 1:04 am

I just looked at the pictures again. If the "significant cracked hose" is running to a black plastic canister, You are right on target! The CEL is an indicator of an emissions problem. The diff hose is neither part of the emissions, nor does it have any sensors on it (other than maybe a tone ring for speed). That black canister IS part of the emissions system. Leaks are common around it on our models.

JeepPilot · **Posted:** Thu Aug 21, 2008 11:16 am

ThunderbirdJunkie wrote:

JeepPilot wrote:

Is it an issue that my breather is torn like it is?? It wouldn't cause an evap leak, would it??

No, but your mudrunning has probably caused it to take some water in.

That evap hose that goes near the tank is probably the cause of your issue.

Tell me if this is correct:

Yes, I have located a significant crack in a hose up in that area signified in the above picture. That is where the crack from this picture is located...

I'm ready and willing to repace the hose, but I'm unaware of the procedures I should take to do so.

JeepPilot · **Posted:** Thu Aug 21, 2008 11:17 am

ThunderbirdJunkie wrote:

JeepPilot wrote:

Is it an issue that my breather is torn like it is?? It wouldn't cause an evap leak, would it??

No, but your mudrunning has probably caused it to take some water in.

That evap hose that goes near the tank is probably the cause of your issue.

Tell me if this is correct:

Yes, I have located a significant crack in a hose up in that area signified in the above picture. That is where the crack from this picture is located...

I'm ready and willing to repace the hose, but I'm unaware of the procedures I should take to do so.

rescu2000 · **Posted:** Thu Aug 21, 2008 11:38 am

It's easy. Just pull the hard plastic lines out of it (be careful not to break them, them may have become brittle). Take that section of hose to Advance and ask for 5 foot of it and a small worm clamp. This is enough to do BOTH the split part and the diff breather tube. Cut the new piece to the same length and stick the hard tubes back in it.

You may be concerned about what is INSIDE of that hose. Nothing. It is a fume collector I think. It's empty. Use the rest of the hose and the clamp to replace the breather tube. You can run it to the same spot it is in, or somewhere higher up if you want to feel more comfortable crossing deeper water. There are three of these tubes you need to raise higher. The tranny one is between the engine and firewall, and a little tricky to get to. The front diff one has a black breather (similar to the white one in the back) and a little circle off to the side. I think it is down on the steering rack. You can pull it off and just zip tie it higher.

JeepPilot · **Posted:** Thu Aug 21, 2008 6:02 pm

Alright, so I got under my KJ and replaced the rubber hoses connected to evap system (black canister) and I replaced and reclamped the rear diff breather hose as well. Here are some pics (sry, not the best quality)...

new hoses connected to the black cannister

replaced rubber hose between two solid plastic hoses

same hose at a different angle

just another shot if some replaced hoses running to the black canister

replaced and reclamped rear diff breather, now sits a little bit higher than stock, as suggested

If replacing these hoses solves the large evap leak problem, should my CEL light go out after 3-5 starts of the ignition? Or should I reset the CEL?

CEL P0442 & P0455

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