Hi NAS,

If you decide you'd like to visit your Jeep dealer and need an additional layer of assistance while working with them, let us know. We're available via direct message and would be happy to help.

Jasmine
Jeep Social Care Specialist

 

It means just as the code states. The PCM has detected that there is a leak somewhere within the EVAP system. It's venting unmetered fuel vapors into the atmosphere and somewhere...it's pissing off a tree or two.

Just because it's a capless system, doesn't rule out components of the filler neck leaking or not sealing intermittently. The EVAP system monitor "self tests" every few key cycles hence the intermittent MIL. It's pretty common for the leak detection pump (integrity monitor) itself to develop a leak or fail internally (hence no visible smoke). Outside of that, you have various other EVAP system components that could leak such as hoses, fittings, seals, fuel tank, tank pressure sensor, charcoal canister, purge solenoid, vent solenoid, all the way to the schrader valve in the EVAP service port.. Generally, if the purge or vent solenoids fail internally, you'll get a different code.

How much fuel was in the tank when the vehicle was smoke tested?

 

The Tank was a full tank, I've also had the smoke test done with around a quarter as well..

sorry for the late response.

 

I have the same issue in my ‘14 GC. That code trips when most often when I leave the garage and there is temperature differences of 20 or so degrees outside to inside the garage.

I bought a simple code reader and clear the fault when it happens. When the code is tripped, the remote starter doesn’t work.

This has happened for a couple of years and does not seem to harm anything. I would love a cheap fix however.

 

I'm back. So I sent it back to the dealer.. It's gone to 2 Jeep Dealers and they said there is no active leak. Yet the store is stored and its coming on? that makes no sense... i've driven my car over 500 miles without luck of the light resetting itself. They've done a couple of smoke tests...from the front and from the rear...
I dont know what else could be triggering this light.... Maybe the gas tank area and the capless not sealing right?? i dont know but it has turned into a burden.

 

Sounds like a PCM reflash may be in your near future. Have the dealer verify the software version is current.

 

No...a pcm reflash will not fix this. Its a 2014....

 

That code is for a small leak. It's a very small leak. I've gotten such a code one time or another on just about every vehicle I've owned. And never been able to find a reason and for me they have always gone away by themselves or I've cleared them.. although sometimes they stay even when cleared for some reason for a few more days. One car would have the light come on about every 3 months. Clear it and things were good for another 3 months. If it was a meaningful leak I don't think it would stay cleared that long. I suspect the gvt made the detection level so low as to be unreasonable and it winds up setting that code when there is no real problem... which makes it hard to find the problem.

 

The EVAP emissions test is part of OBDII mandated by the government. The vehicle has to test all of its emissions equipment its self and set a CEL to get the owner to repair it, if any of the emissions equipment fail the test.

Gasoline evaporates, raw gasoline fumes contribute greatly to ground level ozone and smog. So there is a system to capture all the fumes from the fuel system and prevent them from being released to the atmosphere, instead, stored in a charcoal container to be released into the engine to be burned.

You system is failing the test, at least how the PCM sees it, and thus lighting the light.

Two things;
First the Federal Mandated Standard is far to stringent IMO, its something akin to loss equivalent to a 2 micron hole. So the manufacturers have to come up with a test to find a leak that tiny. And the kicker is, a leak that tiny is virtual no leak at all, so you end up with the catch 22 where the system thinks its leaking, but no can find the leak, so you have to live with the light.

Second, the PCM just knows the system failed the test, it doesn't know if the system is actually leaking or not. The test Equipment, the ESIM or Integrity Monitor that actually performs the test might be out of calibration or failed and thus seeing a leak that doesn't exist. So perhaps replacing that might solve the problem.

Like someone mentioned earlier, this code is telling you there is a small leak in the evap system. At worst, you're venting the tiniest bit of gasoline fumes, it isn't hurting the vehicle and likely not hurting the environment at all. Ask yourself, if they can't find the leak with a smoke test, how much gas fumes could actually be leaking? But the Fed set a standard for the system to light warnings for leaks so small they can't be found, leaving you in the learch.....

Also keep in mind, the remote start often disables itself any time a CEL is on. Using an OBDII scanner to reset the CEL, will result in the Emissions test to restart itself again. It performs the Evap test only when certain conditions are met, but that comes down to, it won't test the Evap right away, it will take a few days to even a few weeks before it performs the test again. So you won't know if a repair attempt worked until a few days or weeks until the light comes back on or not.

 

GREAT NEWS. the dealer finally found the issue and is not fixed.. i hope

it was a purge valve..

thanks for all of your feedback and information.

 

The P0456 code (very small EVAP leak) was caused by the EVAP purge valve on my 2015 JGC Overland, $20 part (P/N CP796). After replacing the leak sensor and o-ring like the web suggested it did not fix the issue. Smoke test also did not show any issue. Postmortem of the old valve shows that the rubber seal was cover with charcoal dust preventing a good seal thus allowing a small leak. I tested the solenoid with 12v, it works fine, hear it clicking. Blowing into the 'CAN' side with voltage off proved the old valve was not sealing properly, air was able to pass through. Took it apart, found allot of charcoal dust around the rubber seal. Cleaned it up with rubbing alcohol and super glue it back together. Retest show the old valve works fine.

 

Thats the vent valve...not the purge valve.

 

This happens when the tank is overfilled on a regular basis and raw fuel leaks into the charcoal canister. Once the fuel pump shuts off when refueling, do not try to add more fuel. For some reason people try to add fuel until the dollar amount on the pump is at an even amount.

 

Thanks for the tip but I do not overfill my tank. I am aware of the consequence with overfill on these new cars so I never overfill. Something else is going on.

 

I had the "very small evap leak" error and after a couple of weeks it went back off. Seems like it pops up on every car I own sooner or later. Most of the time it's a bad gas cap but on these capless systems obviously it's not that.

 

This seems like the right thread. If not my apologies.

My 2013 Jeep GC Overland has been giving the P0456 code. Replaced gas cap. Replaced ESIM and gasket. Still throwing the code.

I checked purge valve and it looks like a clip is missing. Attached image.

If the clip is missing, would that cause the code? Thanks for any help.

 

Check out my thread on this. Hopefully it is helpful:

P0456 - The Culprit FOUND

So, I’ve been getting this code for a couple of months (very small leak detected), and like some, I opted to replace the leak detector piece inside the drivers side wheel wheel, clear the code, then see if it comes back. Cost me $25 and my time. Well, it came back. The next thing for me to...

www.jeepgarage.org

 

Definitely so. The way the system works, every so often it performs a self leak test. The purge valve closes and vacuum is drawn into the system. A pressure sensor checks the pressure in the system for the duration of the purge valve being closed. If vacuum is lost it throws the code. Any leaks on hoses or fittings will cause loss of vacuum during the self test cycle. I had the same thing happen to my daughter's Nissan Rogue and it was a sticky purge valve. that would cause loss of vacuum during the test cycle. They had it mounted behind the right rear wheel well and was prone to corrosion from dirt and water being kicked back from the tire.

 

Good Day All!

Hopefully I am posting in the right thread.

I have been getting an engine light on my 14' Jeep Grand Cherokee Laredo 4WD. The engine light will stay on but turn off after a couple of days.

The last two times i went and had it read its coming back as code: P0456 - evaporative emission system leak. What does this code mean if i do not have a gas cap and have a capless tank.

Jeep did a smoke test and could not detect a leak. Has anyone had this issue and can any one give me some insight of what it may be and a possible cost? I am wondering if maybe a wire of some sort on the sensor is loose..

Thanks so much!

NAS


I know I’m late but were you ever able to figure this out? I’m having the same issue but a few weeks ago I was a little rough pulling the gas nozzle out and since then there has not been a tight seal.

 

Before you get too into it, check out this thread - P0456 - The Culprit FOUND

It's a good cheap fix that has lasted. Try this before spending any real money.

 

Back in August 22 (it's April 23 now) my check engine light comes on. Solid orange. One day when I have time time I drop by the dealership. Guy plugs his device in, runs a code, says it's a pressure leak somewhere in the fuel line. Says it can happen after fueling. Sticks his finger in the gas flap (no cap). Clears the code. Says the issue won't impact drivability. Should be fine, but if the light comes back on, make an appointment and bring it in for them to do a smoke test to determine where the leak is.

Light is off for a few days, comes back on. I don't think anything of it. Fast forward a few days, I'm getting some gas. Clear, sunny day. I hear what sounds like rain. Look underneath- gas is spewing out- picture below. I stop pumping- the leaking stops. It dries off. The tank did take in quite a bit of gas. I got it home, tank didn't go from full to empty or anything crazy- operated normally, no continued leaking. I replace this part, wondering why on earth is there an rubber hose like that, completely exposed, that is susceptible to cracking and leaking like this? What kind of engineering is this? Anyway- no longer leaking gas when pumping, but CEL is on. This month inspection is due, so going back and forth with the dealer to clear the P0455 and P0456, they've so far replaced the purge hose, valve purge, canister, and seal. CEL is, so far, off. But I still need to drive it about 100 miles before I can go back for emissions and stickers, so we'll see. I really wish I saw this thread before I spent about $800 on this malarkey.

 

My P0456 code is now coming back as a permanent code I fixed it at the dealer🙃 what do I do now!? I've took it back 3 times! Going on 4 I can't pass my smog! Any advice?

 

Here' my 2014 Jeep Grand Cherokee Overland story and how I finally figured it out with a smoke test.
Had a gas pump shut off pump fail back in June of 2024, which caused an overflow in my gas capless
intake area. I thought the gas odor was the problem. It wasn't. I started getting P0456 codes 10 days later and 2 more after 2 months time My OBDII gave me the same info, each time. Decided to figure out and fix the problem myself. All the YouTube videos suggested that I replace the ESIM detector near the
gas intake above the LR tire behind the wheel will liner. This was the most likely cause. This part was
only $40 at Auto Zone.....and $80 at MOPAR. Got the ESIM and installed it in 30 minutes. Sadly, I got
the same code 3 more times into late October 2024.

So now what? There must be some other place in the EVAC system that is leaking or failing. So,
just got a smoke test at my local auto shop ($250). This puts white smoke pressure in the EVAC
system all over including the engine compartment. Sure enough, little puffs of white smoke popped up
in a long hose called the purge hose which recycles vapors into to cylinders for combustion. Nasty
cracks vertical and horizontal where the rubber end fits over the purge intake. Pretty sure this was
it. New Purge hose is for the 2014 is MOPAR Part # 68189075AE....and ONLY $50! Or even cheaper
just seal the crack with Gorilla Glue! 5 cent solution. The ESIM is also a good thing to replace every
10 years or so. They get dirty fast. I expect my P0456 to go away permanently now, but I can
always to a reset. I think it counts 20 instances of this tiny leak before it codes on the idiot light.

Roger

 

I am having same problem in my 2014 jeep grand Cherokee

 

My parents drive a 2018 grand Cherokee with a capless system, apparently for their Jeep the filler seal is recalled.

 

The PO455 code came on in my 2011 Grand Cherokee and my reader indicates it is not a severe leak - From what I read on here the PO 456 & PO 457 codes show up with more severe leaks - Has any one else came to that conclusion ? KD

 

No... a ocm reflash will not fix it...its a 2014...