Check Engine Light P0456 - JeepForum.com
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post #1 of 30 Old 09-29-2010, 05:03 AM Thread Starter
Elt31987
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Check Engine Light P0456

So got my first CEL since i bought it 2 1/2 Years ago. P0456. After reading its referring to a small leak in the Evaporation System. First everyone says to check the Gas Cap which i turned off the engine, Took the cap off, put it back on and made sure it clicked a few times. The cap is a Mopar Locking Cap that I've had since i bought the Jeep. After removing the cap and putting it back on the light is still on after i drove about 22 miles to work. I don't know how long it takes for the code to disappear if that was the issue but the light is still on. So basically I'm going to hope its off when i leave work today and if not ill put my girlfriends Locking Mopar Cap from her Patriot on mine and see what happens. Any other suggestions to look for?


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2008 KK Liberty
Inferno Red
Daystar 2" Spacer Lift With SkyJacker Hydro Shocks
JBA Gen 5.5 Upper Control Arms
Rokmen Riddler 8.25 Differential Cover
2 KC Slimlite 100 Watt Driving Lights on JK Light Bar
245/75/16 All Terrains
Mopar Front Tow Hooks
Mopar Rear Tow Hook
Mopar Skids
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post #2 of 30 Old 09-29-2010, 12:18 PM
richd
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There are 2 causes of PO456,I would swap caps to see if that helps,If not the there a small leak somewhere in the EVAP:
  • Fuel tank cap is damaged, loose or the wrong part number
  • Small leak present somewhere in the EVAP system
Here is how to reset your code:

To reset your engine codes:
Remove the negative terminal of your battery (10mm wrench).

Turn your ignition key to START and hold it there for about 15 seconds.
Turn your ignition key to OFF and remove it.
Connect the negative terminal of your battery.
Start but do not hit the throttle. Idle for about 10/15 seconds then turn off.
Restart the truck and drive as usual. It will take at least 12 starts and 48 miles to fully retune the computer. Hard Codes leave a shaddow for 40 full cold starts.
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post #3 of 30 Old 09-29-2010, 04:29 PM Thread Starter
Elt31987
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So i inspected the Evap Box and hoses and didnt see any holes or tears etc. BUT, i could smell gas from the Cap so i think its leaking. So i disconnected both battey terminals for 30 minutes and threw my original Gas Cap on that i found laying around and so far so good. Ill keep you guys updated over the next week. Wish me luck.

---------------------------------------------------
2008 KK Liberty
Inferno Red
Daystar 2" Spacer Lift With SkyJacker Hydro Shocks
JBA Gen 5.5 Upper Control Arms
Rokmen Riddler 8.25 Differential Cover
2 KC Slimlite 100 Watt Driving Lights on JK Light Bar
245/75/16 All Terrains
Mopar Front Tow Hooks
Mopar Rear Tow Hook
Mopar Skids
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post #4 of 30 Old 09-29-2010, 05:04 PM
richd
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Your doing it the right way,Good Luck
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post #5 of 30 Old 10-05-2010, 09:03 AM
KUHawkhead
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We had the same thing happen on our 08 this past week. Had a mechanic friend of mine check and reset the light. He told me that it would reset itself if it's nothing out of the ordinary within a week on its own.
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post #6 of 30 Old 10-17-2011, 04:18 PM
VMF
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i just got this code today did yours dissapear after you changed the gas caps?
my jeep had the gas tank replaced under warranty and it was at the dealership for spider gear replacement over a week ago. since the evap canister is right in the proximity, i wonder if these things are related....

___________________________
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2009 JK Rubicon. Black
2004 UCF31. Black
2001 EM2. Inca pearl
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post #7 of 30 Old 10-18-2011, 06:37 AM Thread Starter
Elt31987
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Yup hasnt happened since.

---------------------------------------------------
2008 KK Liberty
Inferno Red
Daystar 2" Spacer Lift With SkyJacker Hydro Shocks
JBA Gen 5.5 Upper Control Arms
Rokmen Riddler 8.25 Differential Cover
2 KC Slimlite 100 Watt Driving Lights on JK Light Bar
245/75/16 All Terrains
Mopar Front Tow Hooks
Mopar Rear Tow Hook
Mopar Skids
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post #8 of 30 Old 10-18-2011, 08:32 AM
VMF
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interesting... i wonder if my gas cap is bad or its just my lack and one of the hoses got a crack...

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2004 UCF31. Black
2001 EM2. Inca pearl
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post #9 of 30 Old 10-20-2011, 09:57 AM
VMF
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well the light dissapeared 2 days after. i guess it was the cap, i removed it for inspection, no cracks, put it back in tight and it dissapeared. i was about to swap the gascapts between the liberty and the rubicon but decided to start n check first and it was gone! yey!

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post #10 of 30 Old 10-20-2011, 11:13 AM
tjkj2002
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Locking gas caps are known for leaking and don't do much good when a $5 tool is out there to easily remove them.

For $12 for a new gas cap it's just a good idea to change every year or at least every 2 years.

'02 Liberty sitting on 35" tires,HP44,RockJock60,and AtlasII t-case
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post #11 of 30 Old 10-20-2011, 12:03 PM
VMF
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neither jeep has a locking one, just regular OEM caps that came with both cars. rubber seal seems to be fine i think i just didnt tighten it up enough after last refill.

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post #12 of 30 Old 10-14-2014, 09:34 PM
beherenow
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so last friday the engine light came on... damm... just now i did the car key trick and the code back in the od came as P0456.... i still have the original 5 year gas cap... guess i"l hace to replace it and cross my fingers this gets resolved
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post #13 of 30 Old 10-15-2014, 04:05 AM
josworth
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Helpful tip..... visual inspection is pretty worthless with emissions regulated gas caps. Similar to a radiator cap, they contain a pressure valve that wears out. If your state has emissions testing, the test center will have a cap pressure tester. In Ohio, our e-check station will check your cap for free.

Some auto parts stores will test them as well.

Jeff

2010 Honda Crosstour AWD-V6
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post #14 of 30 Old 10-19-2014, 11:13 PM
beherenow
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changend my cap and the msg went away, yes!
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post #15 of 30 Old 01-10-2015, 09:41 PM
SpecialK2000
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P0456....if it's not your gas cap.

Okay so everybody knows by now to change their gas cap. Whoopty do. If you've changed your gas cap and your CEL is still glowing bright as the sun read on. If your light went off, congratulations.

I've been battling my CEL for over a year now and I have finally won. What you need to do is check every inch of tubing. I guess a smoke test should work but I've gone through smoke tests and each one has come back with a 'we couldn't find the leak'. I don't think the smoke test is as straight forward as it sounds. If it's not done right, the smoke won't make it through the whole system.

I found my issue in the metal tube running from the EVAP cannister to my gas tank. It was all rusted but it looked okay. I was fed up one day and just took it out. When I blew into it, I sounded like Ian Anderson of jethro tull. I replaced it and the light still would not go off.

I went out and bought a code reader from sears for $70 so I could clear the code without having to disconnect the battery and so I could really solve this problem.

My light kept coming on after clearing it...until finally one day I guess I played the right combination of turning off the CEL and filling up my tank. My light stayed off for over 200 miles. I brought her in and she passed inspection. Light is still off after 250 miles.

Bottom line....check all your lines, connectors, EVERYTHING. Buy the code reader too, then erase the code and go fill up your tank.

Good luck.
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