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Unread 09-26-2011, 03:18 PM   #1
orb
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Unhappy p0456 and p0442 Small/Medium Evap leak

So my CEL has come on and I pulled the codes the other day. Also cleared them and they came back.

Quote:
P0456 (M)

Evaporative Emission Control System Leak Detected (very small leak)

A 0.020 leak has been detected in the evaporative system. See TSB's 25-001-02A, 18-002-03 and 25-004-01. Also, possible faulty or loose gas cap.

(Also see Notes in P0455 above). Does customer regularly commute on a steep grade (down hill grades in excess of 10%? Has the Leak Detection Pump Operation and Diagnosis booklet (Publication No. 81-170-000606) been used to assist in the diagnosis?

Review and if necessary, perform TSB 18-010-02. Be sure to completely read the TSB. The fix for the condition is a PCM replacement, not a reprogramming of the controller. Be sure that there is not any leaks in the system. This TSB applies in a very limited number of cases and usually in mountainous regions. TSB 18-010-02 Is a PCM replacement correct an erroneous MIL illumination for SAE P0456 that sets when driven on steep grades.
Quote:
P0442 (M)

Evaporative Emission Control System Leak Detected (medium leak)

A 0.040 leak has been detected in the evaporative system. (A faulty gas cap may cause this code). Also see TSB 25-001-02A. Note: The respective Powertrain Diagnostic Procedures Manual will direct the technician to determine if the vehicle evaporative system has an external system leak. Examples of some external system leaks are: a loose gas cap, a disconnected evaporative system hose, or a loose hose connection. Remember that the evaporative system may also have an internal system leak. This internal leak may be caused by an intermittent or permanently stuck open Duty Cycle Purge (DCP) valve. This leak source is considered to be internal because any escaping emissions enter into the engine system and not directly into the atmosphere, unlike an external leak. An internal leak may cause one of the above DTC?s. Possible causes of a stuck open (intermittent or permanent) DCP valve are: 1. Corrosion due to system moisture or possible water intrusion into the system.
Only thing I have done so far is look under the hood for any cracked or broken hoses. Nothing so far but I didn't spend a lot of time. I also tried to find the cannister and hoses that are in the rear drivers side by the wheel. I didn't get all the way under but I couldn't see anything obvious. I know I have to remove the wheel so I plan on doing that tonight. What else will need to be removed to get to these hoses? Do I have to take the bumper cover off? Lower the gas tank? That would be a real PITA if I need to do both.

Any tips or advice before I lift it up tonight and get under there? I ordered a new gas cap (updated one) so hopefully that will be here this week. I kind of doubt that is the problem though, I checked mine and it looked fine but who knows...any help is appreciated!

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Unread 09-26-2011, 05:17 PM   #2
straty1987
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i had P0456, a new gas cap form jeep fixed it.

turns out the gasket goes bad and looks good so they updated the cape. might be worth a shot spending $20 before replacing hose.

part number 52124512AA http://www.justforjeeps.com/factorygascap.html

i know that canister is annoying to work around.
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Unread 09-26-2011, 05:29 PM   #3
orb
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http://www.amazon.com/gp/product/B0050ISS7Y Same 52124512AA part number and only $10.43 shipped! Hopefully this solves the problem, that would be soooooooo exciting.
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Unread 09-26-2011, 06:09 PM   #4
straty1987
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Quote:
Originally Posted by orb View Post
http://www.amazon.com/gp/product/B0050ISS7Y Same 52124512AA part number and only $10.43 shipped! Hopefully this solves the problem, that would be soooooooo exciting.
did u order form him?
how it work out?
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Unread 09-26-2011, 06:10 PM   #5
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Just ordered today. I'll let you know once I get it.
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Unread 09-26-2011, 06:16 PM   #6
straty1987
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cool post it and make sure the part number is correct because it is used (slightly they say) and they can mix in old ones.
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Unread 09-26-2011, 07:43 PM   #7
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Definitely, hopefully it arrives soon and with the proper model number.

I just remembered this, the second code p0442 had a "(pending)" at the end. Does that mean the test was not fully completed yet? Im talking about the jeep's check that throws the CEL, not the OBDII reading the codes.
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Unread 09-26-2011, 09:26 PM   #8
straty1987
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P0442 says it might be the gas cap as well.
i don't know what pending might of means never seen tat before sorry
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Unread 09-27-2011, 03:38 PM   #9
WJWKXJZJ
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Wj

I got those same codes. Turned out to be a rotted hose going into the charcoal canister. The access to the pump/canister is the biggest challenge, as 2002-2004 it's moved from the engine compartment to under the driver's side rear wheel well, below the filler neck.
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Unread 09-28-2011, 07:04 AM   #10
dutch724
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To get to that canister you have to take off the rear bumper cover and to service the hoses you need to drop the hitch and the gas tank about 6 to 8 inches. Fun stuff I have done this job 2 times and replaced hoses and the code goes away and comes right back again later down the road. The code is back again so this will be my 3rd time doing....whenever i get the motivation to do it again.
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Unread 09-28-2011, 10:27 AM   #11
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Quote:
Originally Posted by dutch724 View Post
To get to that canister you have to take off the rear bumper cover and to service the hoses you need to drop the hitch and the gas tank about 6 to 8 inches. Fun stuff I have done this job 2 times and replaced hoses and the code goes away and comes right back again later down the road. The code is back again so this will be my 3rd time doing....whenever i get the motivation to do it again.
Wow thats kind of awful. I might just take it to a shop if I have to take the bumper and hitch down if it really does come back often. Really hoping the gas cap fixes it.
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Unread 09-28-2011, 11:19 AM   #12
dutch724
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IDK if it comes back that often or maybe I'm not fully fixing it. i have found that maybe the hose popped off the connections or something like that. The hose that I have a problem with cracked at the ends, this is the hose that has a bunch of bends made into it. That hose is a $50 hose and I wasn't going to spend that on a hose that cracks when it drys out. So I repaired it with a piece of fuel hose. Which worked...... so I thought. Then code came about a month later. But you never know maybe it did work and this time it is for a different hose that cracked that has to do with the same system.
I did read in the service manual there is 2 hoses under the hood that go into the back of the valve covers that can crack and cause the same codes to come up. Check those first before digging under the bumper cover.

The way I handled the gas tank and hitch was I used a jack to hold it up and then I was able to lower it at a controlled rate and jack it back up when I was ready to put everything back together.

As I said one of these days when I have the motivation i'll get back under there and see what the code is all about this time.
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Unread 09-29-2011, 08:18 AM   #13
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When I did the check and repair on my 2002 Overland I only removed the filler panel in the wheel well and the metal mounting brackets for the canister and pump. I was able to access all fuel lines but not the vapor lines to the top of the tank where they enter the tank, you will have to drop the tank for that. You can test them with a vacuum/fuel pressure gauge and Mighty Vac. Alternate pressure and vacuum to the tank using the pump and time the leak down using the gauge. If you've ruled out the filler neck and the cap, that would be the next test I'd try before dropping the tank.

2 stainless lines run forward into the engine compartment to the electronic purge valve. It's on the driver's side adjacent to the valve cover area. Should be shown in the underhood vapor hose diagram too.

The hoses going to the pump and canister are in a more vulnerable area than the top of the fuel tank so I'd go through them with a fine toothed comb first.
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Unread 09-29-2011, 10:02 AM   #14
orb
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Quote:
Originally Posted by WJWKXJZJ View Post
When I did the check and repair on my 2002 Overland I only removed the filler panel in the wheel well and the metal mounting brackets for the canister and pump. I was able to access all fuel lines but not the vapor lines to the top of the tank where they enter the tank, you will have to drop the tank for that. You can test them with a vacuum/fuel pressure gauge and Mighty Vac. Alternate pressure and vacuum to the tank using the pump and time the leak down using the gauge. If you've ruled out the filler neck and the cap, that would be the next test I'd try before dropping the tank.

2 stainless lines run forward into the engine compartment to the electronic purge valve. It's on the driver's side adjacent to the valve cover area. Should be shown in the underhood vapor hose diagram too.

The hoses going to the pump and canister are in a more vulnerable area than the top of the fuel tank so I'd go through them with a fine toothed comb first.
Thanks man, that's actually really helpful. I'll crack that filler panel open this weekend and take a look. I should also check under the hood a bit more carefully.
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Unread 10-07-2011, 07:59 PM   #15
orb
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No codes yet, the gas cap may have worked!! So excited, hope it stays this way.

The cap didn't have a part number on it when it came, it was only listed on the amazon site. Looked brand new though, couldn't tell it had been used.
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