permanently defeating the 0456

daver · Post by **daver** » Sun Sep 03, 2006 11:19 am

Is anyone familiar with how the evap system functions, particularly in relation to how it determines conditions for lighting a CEL?

I would like to permanently either electrically or mechanically defeat the 0456 code and corresponding CEL.

I randomly get it every few months.. reset the computer a few times, futz with the gas cap and it goes away for a few more months... short time later cycle begins again.

ewetho · Post by **ewetho** » Thu Sep 07, 2006 6:51 pm

Check your gas cap and fill pipe seating surface. If all is well no dings or nicks in it then try a new cap and make sure not to fill up while running.

SlvrACR · Post by **SlvrACR** » Thu Sep 07, 2006 6:54 pm

My buddy had the same prob. He had a small pin hole in his gas tank on the top. We replaced it and never came back on. He had the same bs you did

BlackRoseRacing · Post by **BlackRoseRacing** » Thu Sep 07, 2006 7:08 pm

As per DCx:

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.

Post by **Diablo0** » Thu Sep 07, 2006 10:49 pm

I got the same code this past weekend on the white car. My cap was a tad loose though so I disconnected my battery, reconnected it, tightened my cap up and I'm waiting to see if it'll come back on here in a few weeks or so. I might be in the same boat as you though so in a few weeks or months I could be trying to fix the same issue.

PBz · Post by **PBz** » Tue Sep 19, 2006 12:47 am

i kept throwing the same code fella's and ladies.
upon running several forced leak tests with the DRB III found that the hose going into the NVLD PUMP was split it is quite common on the 2gn's
here's the picture

hose 14/15 going into canister
or
hose 2

usually theres enough hose to cut past the split and reslide it back over the nipple

Post by **Diablo0** » Tue Sep 19, 2006 1:18 am

Good deal... I'll have to check that out. I do remember when swapping out to my NVLD pump on the white car the hose that goes to the filter was sort of a stretch fitting over the male end. I'd almost put money on it thats where my leak is, in which case buying another clamp (#13 in the diagram- 4885705AA) could fix the problem by making it more air tight if thats where the leak is.

neonxrt · Post by **neonxrt** » Wed Apr 30, 2008 3:17 pm

PBz wrote:i kept throwing the same code fella's and ladies.
upon running several forced leak tests with the DRB III found that the hose going into the NVLD PUMP was split it is quite common on the 2GN's
here's the picture

hose 14/15 going into canister
or
hose 2

usually theres enough hose to cut past the split and reslide it back over the nipple

Anyone know where I can find a P# for hose #4 in thie picture??
I noticed some small cracks in the base of it where it attaches to the canister, that must be what's giving me the P0456 code.

Danteneon · Post by **Danteneon** » Wed Apr 30, 2008 4:49 pm

You have probably figured this out from my post, but I'll put it here as well. The above illustration isn't correct for all Neons. Actually, I'm not sure that is even a Neon picture. But the '01-'02 were different than the later (03 - up) Neons.

Here is the link to my how-to on this (for future reference)

http://forum.2gn.org/viewtopic.php?t=28793&highlight=

kevo · Post by **kevo** » Wed Apr 30, 2008 5:22 pm

Danteneon wrote:You have probably figured this out from my post, but I'll put it here as well. The above illustration isn't correct for all Neons. Actually, I'm not sure that is even a Neon picture. But the '01-'02 were different than the later (03 - up) Neons.

Here is the link to my how-to on this (for future reference)

http://forum.2GN.org/viewtopic.php?t=28793&highlight=

I was looking for your thread the other day. you are the man!

I wonder if this will help me with my problem. i have had P0040 and P0441 for over a year now. its not my gas cap as i always tighten it.

Danteneon · Post by **Danteneon** » Wed Apr 30, 2008 5:27 pm

Could be. Just check the hose condition at the points in the pictures I have up. Hope it helps you