How I Fixed My Code P0456

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How I Fixed My Code P0456

Post by Retired BLM Rig » Sat Dec 31, 2016 2:30 am

Re: Check engine light on due to code P0456 (small evaporative system leak detected). All of this information applies to a 2008 PW, but the theory should apply to any vehicle (sometimes they change the name of system components from year to year).

It's been a couple months since my check engine light first came on because of this code. When I read what it was on my scanner, I cleared the code and checked my gas cap for tightness and forgot about it since it was nothing serious. But then it started repeating the same code every week or two, so I figured I better get to the bottom of it.

The most common failure is a bad rubber seal on the gas cap, even though I couldn't see any cracks or deformities, I decided to replace it since it was the original eight year old cap. I got an O.E. Mopar replacement, cleared the code again and waited to see if it would come back on. Sure enough, after a few more trips to work, the CEL popped back on with the same code. :evil:

Next on my diagnostic list was to carefully check all of the rubber and plastic lines in the evaporative system for cracks, splits or loose connections. I started at the evap/charcoal canisters mounted just in front of my fuel tank and followed each line to and from the canisters throughout the entire system. The hardest ones to check are on top of the fuel tank, but a good flashlight and mirror can help with those. I didn't find any problems with the lines, so now it was time to focus on components.

The first and most obvious component is the canister. It's pretty well protected between the frame rails, but you never know when a stray stone or piece of road debris may get kicked up there and damage something. Mine looked good with no signs of splits or cracks.

Every evap system has a vent/inlet somewhere, mine is above the transmission bell housing.
001.jpg
If pressure needs to be vented or air needs to be drawn in, this is where it happens.
The cap is just an open restrictor to stop debris or bugs, like mud dobbers, from building a nest and plugging the vent line.

The next component inline is the filter, this is to stop any dust from entering the evaporative system. It's a mini air filter inside a plastic housing.
002.jpg
My filter sits on top of the evap/charcoal canister assembly.
The next component is called the "Evaporative System Integrity Monitor" (ESIM for short). It locks on to the canister. This is a double weighted check valve that allows pressure venting or vacuum relief at predetermined pressures based on the weight of the check valves.
003.jpg
The ESIM is the bad boy that will turn on your check engine light if it sees that pressure/vacuum isn't being maintained in the system. It's a leak detector, that's what the two wires are for.
To remove the ESIM, lift up the locking tab and rotate it 45º clockwise.
004.jpg
There's an o-ring under the ESIM, make sure it doesn't get lost and check it's condition.
007.jpg
The ESIM is glued together and is supposed to be non serviceable :thppt: . Looking inside the ESIM you can see that a layer of superfine dust made it past the filter media and took up residence on the check valve causing it not to seal.
005.jpg
006.jpg
My solution was to spray aerosol brake cleaner into the ESIM, shake it around and then quickly blow it out with compressed air. I did this two or three times until it looked clean. Make sure not to let the chemical sit for too long as it will ruin the rubber check valve (spray it in, shake and blow it out). The ESIM is available to purchase as an individual part for $30-40, but why buy it if you can clean it.

The next thing I did was blow out the vent filter and lines (a rather impressive cloud of dust). In fact it wouldn't be a bad idea to make this an annual maintenance item if your truck spends a lot of time off road or in dusty conditions.
008.jpg
Blowing out the vent line.
It's been a couple weeks since I did all this work and so far no check engine light and no pending codes. If this hadn't fixed it, other components to check would include the purge solenoid valve (under the hood), fuel fill neck and hoses, fuel pump/sending unit & o-ring and finally the fuel tank.

After seven years of government work in the desert, the dust finally took its toll. Luckily I was able to find it and fix it with the investment of a little time and effort. I hope this will help someone else that may be experiencing the same problem and help save some money and a trip to the dealer/shop.

Happy New Year!!! :patriot:

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Re: How I Fixed My Code P0456

Post by waldo » Sat Dec 31, 2016 7:53 am

Good info and post. Thanks.
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Re: How I Fixed My Code P0456

Post by cruz » Sat Dec 31, 2016 12:00 pm

waldo wrote:Good info and post. Thanks.
X2
While we're on the subject, here is another P0456 code problem that I had a while back ...
http://forum.powerwagonregistry.org/vie ... 456#p53100
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Re: How I Fixed My Code P0456

Post by DamageWagon » Sat Dec 31, 2016 12:05 pm

Thanks man, I'm going to have to try this on my truck. I'm having the same issues and its spent a lot of time in dust and mud. Great write up, hopefully to something easy on mine as well!


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Re: How I Fixed My Code P0456

Post by flattire » Sat Dec 31, 2016 12:52 pm

WOW!

This is the best "how to fix" write up of anything I have seen . :rockon:

In focus photos with proper lighting.
Arrows and comments for details.
How to do it and materials to use procedure.

In school terms a "100%" grade. :patriot:

Future articles suggestions: :secret:

Replace broken exhaust studs.
Tie rod ends and ball joint troubleshoot (and replace).
How to grease driveshaft.
Tranny and diff service.

And if that isn't enough:

How to fix "serv4wd" light for under $100.00. :rofl: ( This might be a challenge.)

:cheers:

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Re: How I Fixed My Code P0456

Post by TwinStick » Sat Dec 31, 2016 3:07 pm

AWESOME write up,pics & commentary ! :notworthy:

And really, what is the actual purpose of all that plastic crap ? :cash: :cash: :cash: :cash: :cash: :cash: :cash: :cash: :cash: :cash: :cash: :cash: :cash: :cash:

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Re: How I Fixed My Code P0456

Post by flattire » Sat Dec 31, 2016 7:25 pm

A simple concept gone crazy by regulation.

What started as a charcoal filter to absorb gas fumes has become this system. I had no idea all this stuff was even there.

Plastic = cheap to make ....sure to fail....expensive to replace. :doh:

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Re: How I Fixed My Code P0456

Post by BigRed2007 » Sun Jan 01, 2017 9:12 am

Great write up. Hopefully I'll be able to find it when I get a chance to try to fix that code. I've had it for at least the last five years....

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Re: How I Fixed My Code P0456

Post by RustyPW » Sun Jan 01, 2017 4:13 pm

Excellent write up! :rockon:
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Re: How I Fixed My Code P0456

Post by adeluca73 » Mon Jan 02, 2017 9:38 am

Very thorough. What a giant PIA for a system that's much like a vestigial organ....useless
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Re: How I Fixed My Code P0456

Post by TwinStick » Mon Jan 02, 2017 9:26 pm

Retired BLM Rig wrote:Thanks for the feedback guys! :patriot:
1gy3xh.jpg

:lol: Thats the OLD MIMITW. You got to update ! :lol:

https://www.youtube.com/watch?v=8KqjvM7r2xY

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Re: How I Fixed My Code P0456

Post by DamageWagon » Tue Jan 10, 2017 2:04 am

So I followed your information there over the weekend and cleaned out my ESIM/NVLD. I took some pictures so people could see a little more. Brake cleaner and air dos perfect, it was obvious how much better it moves now. There is still dust inside it somehow that I can't get out. Oh well. You were right about how much dirt gets in that filter! I swiped my finger inside the ESIM to show the fine layer of dust that accumulates. ImageImageImageImage


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Re: How I Fixed My Code P0456

Post by DamageWagon » Tue Jan 10, 2017 2:18 am

So I followed your information there over the weekend and cleaned out my ESIM/NVLD. I took some pictures so people could see a little more. Brake cleaner and air dos perfect, it was obvious how much better it moves now. There is still dust inside it somehow that I can't get out. Oh well. You were right about how much dirt gets in that filter! I swiped my finger inside the ESIM to show the fine layer of dust that accumulates. ImageImageImageImage


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Re: How I Fixed My Code P0456

Post by stamm20 » Tue Jan 10, 2017 8:59 am

Great write up thanks man!!! I have a few EVAP codes in right now

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Re: How I Fixed My Code P0456

Post by socalluke » Wed Aug 07, 2019 8:34 pm

No codes, but now, even the slow flowing gas station pumps are shutting off every 30 seconds, as I try to fill the gas tank.

-> Any tips for how to remove the filter, so I can blow air out the vent tube?

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Re: How I Fixed My Code P0456

Post by Retired BLM Rig » Thu Aug 08, 2019 9:22 am

socalluke wrote:
Wed Aug 07, 2019 8:34 pm
No codes, but now, even the slow flowing gas station pumps are shutting off every 30 seconds, as I try to fill the gas tank.

-> Any tips for how to remove the filter, so I can blow air out the vent tube?
It's just held on by one or two 10mm hex fasteners, very simple to remove and blow out. Be prepared for a large dust cloud.

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Re: How I Fixed My Code P0456

Post by Retired BLM Rig » Mon May 24, 2021 2:17 am

Well it's been 4-1/2 years since my original post and my check engine light came back on for this same code a couple months ago. I have a mandatory smog test coming up next month, so I figured I better get to the bottom of it. I revisited all the same diagnostic procedures as discussed originally, but to no avail. It came down to having to do a smoke test on my evaporative system to find the source of the new leak. It was such a small leak on top of the fuel tank, I had a hard time finding it.

A smoke machine generates smoke for a visual aid in locating a leak, but there's also a flow meter. There's high flow while the system is being pressurized, but if it's truly sealed then it should slowly decrease to zero flow. The only way I was able to achieve zero flow was to push down on one of the plastic lines on top of the fuel tank. After using a mirror to get a closer look, I could see that one of the plastic fittings was cracked on top of the liquid/vapor separator. Time for a new fuel tank. :cash:

I debated trying to see if I could repair the leak, but after discovering that a new tank was still available, I decided to just bite the bullet and be done with chasing leaks in an old, dry, brittle, plastic tank.
IMG_3295.JPG
On this tank the liquid/vapor separator sits in the middle of the tank.
IMG_3299.JPG
It has two quick disconnect lines and one sealed line.
IMG_3302.JPG
It was the sealed line that had the cracked fitting.
IMG_3303.JPG
With almost 130K miles, I decided to replace the fuel pump while I was at it. I opted for a VDO unit, since they're an OEM supplier and make a quality product.
IMG_3310.JPG
Here's the new tank and pump ready to go back in.

It's been a week since I did the repairs, no codes, no check engine light. Now it's ready for the biannual smog test. :patriot:

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Re: How I Fixed My Code P0456

Post by POk3s » Fri Aug 06, 2021 4:49 pm

Great stuff! I spend a good amount of time on dry dusty roads and at 94,000 miles, it’s only a matter of time before this code emerges! Thanks so much for all the info…and further info!

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Re: How I Fixed My Code P0456

Post by fu227 » Sun Aug 15, 2021 9:53 pm

Nicely done
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Re: How I Fixed My Code P0456

Post by jeep_boy02 » Thu Aug 26, 2021 1:46 am

So I've had a roaming evap light. Started with cap, then a small leak. Had dealer fix it while getting an oil change and a day later I get a large leak!

So I finally got around to opening my evap smoker.... didn't even take a whole minute to find this

It's the line right in the middle of the fuel tank, which I can't find so I'll probably cut it out and slip some hose in there.

Image

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Re: How I Fixed My Code P0456

Post by RustyPW » Thu Aug 26, 2021 4:39 pm

jeep_boy02 wrote:
Thu Aug 26, 2021 1:46 am
So I've had a roaming evap light. Started with cap, then a small leak. Had dealer fix it while getting an oil change and a day later I get a large leak!

So I finally got around to opening my evap smoker.... didn't even take a whole minute to find this

It's the line right in the middle of the fuel tank, which I can't find so I'll probably cut it out and slip some hose in there.

Image

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I had the same problem on my Grand Cherokee. To replace the line. You have to buy the whole fuel tank. :shock: I cut the bad section out, and used a fuel line hose and 2 hose clamps. Had a critter chewing on the line at my stepson's place up in Bailey Co.
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Re: How I Fixed My Code P0456

Post by jeep_boy02 » Fri Sep 03, 2021 1:29 am

Yep, cut out 2" and slipped on a 4" piece of vacuum hose. Cinched it down with a couple zip ties. Back to no MIL and and no CEL

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