P0456 code: Suggestions?
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Tuned
Joined: Jan 2012
Posts: 317
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P0456 code: Suggestions?
I'm getting a P0456 Evap System Leak code on my 2004 Ranger 4.0.
Doing a Google search I get things like the gas cap, the charcoal canister, the evap lines... may be at fault.
I cannot do a smoke test, which is the best way to find the leak, so does anyone have an educated best guess on where to start?
Doing a Google search I get things like the gas cap, the charcoal canister, the evap lines... may be at fault.
I cannot do a smoke test, which is the best way to find the leak, so does anyone have an educated best guess on where to start?
Fleet Mechanic
Joined: Sep 2007
Posts: 1,726
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From: down south
most common thing is the gas cap. I dont know if the system resets itself right away or not. But I think I would try resetting the computer and see if it comes back. You might have just not had the cap tight after one gas stop and its corrected itself since. If it does, then you can start exploring the system.
Moderator
Joined: Jan 2004
Posts: 13,851
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From: SW Va
^+1 on the gas cap as being a good suspect. If the problem came after filling the gas tank, maybe you over filled, or filled with the engine running & if so as has been suggested, try resetting the computer & see how it goes.
If no joy on the reset, hook up your ELM scan tool & running FORScan diagnostic software on the viewing device of your choice as discussed here, https://www.ford-trucks.com/forums/1287684-low-cost-elm-scantool.html, have it call up the evap system tank pressure sensor & monitor it to see if pressure is changing, as that could offer up a clue on which end of the system to begin inspecting or testing.
It should be able to activate the purge control valve to make sure its working too, as it's a common problem part. Once you have an idea which end of the system to suspect, use your nose to sniff for fuel vapor aroma. If you still can't spot the problem like a dry rotted hose, loose tank fill hose, faulty gas cap seal, query your local auto parts stores to see if they have a smoke machine in their "Loan-A-Tool program, or rig one with a length of tubing attached to a handy vacuum line & blow some Swishers-Sweet cigar smoke in the line & look, or sniff for smoke leaks & let us know what you find.
If no joy on the reset, hook up your ELM scan tool & running FORScan diagnostic software on the viewing device of your choice as discussed here, https://www.ford-trucks.com/forums/1287684-low-cost-elm-scantool.html, have it call up the evap system tank pressure sensor & monitor it to see if pressure is changing, as that could offer up a clue on which end of the system to begin inspecting or testing.
It should be able to activate the purge control valve to make sure its working too, as it's a common problem part. Once you have an idea which end of the system to suspect, use your nose to sniff for fuel vapor aroma. If you still can't spot the problem like a dry rotted hose, loose tank fill hose, faulty gas cap seal, query your local auto parts stores to see if they have a smoke machine in their "Loan-A-Tool program, or rig one with a length of tubing attached to a handy vacuum line & blow some Swishers-Sweet cigar smoke in the line & look, or sniff for smoke leaks & let us know what you find.
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Tuned
Joined: Jan 2012
Posts: 317
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I cleared the code yesterday. The lamp was off, for the first time, but the code was still showing up on the scanner. Drove around 50 miles today. Got some gas half way and the code has not come back.
Will give it some time, though, as I've had this same issue for many months. These codes have a way of returning. Just need to get past emissions.
Thanks for the replies.
Will give it some time, though, as I've had this same issue for many months. These codes have a way of returning. Just need to get past emissions.
Thanks for the replies.
Tuned
Joined: Oct 2013
Posts: 353
Likes: 4
And if the emissions test involves plugging into the vehicle and looking for DTC's, they'll should/will find DTC P1000, the system readiness incomplete code, and when that happens they know that almost every single time this occurs, it's because the driver cleared codes prior coming to the emissions booth and that he is trying to hide something. Depending on how testing works in your state/area, you may have to come back for another test after P1000 clears (ie, drive awhile to clear P1000 and if the original code promptly returns they you probably will need to fix the cause of the original problem in order to be 100% code-free for testing if that's how it works in your area, as it is where I'm at.). 
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spinnr
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Sep 1, 2011 08:13 AM
