P0456 Very Small leak

Paulie77 · Mar 9, 2024

Just figured i would post this as an FYI

My wife said that the car is rough starting after filling up with gas. Also a check engine light came on for a P0456.

I thought maybe the capless fuel filler and cleaned that and sprayed a bit of silicon on the emergency filler tube then proceeded to insert it into the filler neck a bunch of times. Hopefully my neighbors werent watching. Cleared the code. Next fill-up same issue.

I ordered a new purge valve (L1MZ5K291M). Replaced it last week. Cleared codes. So far so good even after a fill up.

EDWYER · Mar 9, 2024

SFD295 · Feb 9, 2026

I know this is a very old post, but I was looking for the correct part number for the EVAP purge valve hose to correct P0456 and P0496 DTCs, and this one mentioned here is not it. The correct part number is GL3Z-9B325-B.

I don't want someone to make a mistake and order the wrong part, especially because the correct part is described as a "mount bracket", just like this incorrect one posted here is, except the part here is an exhaust mount bracket, not the EVAP part. But the two can easily be confused because of the weird OEM description.

MattJ716 · Monday at 1:28 PM

Bringing this post up again just because I have encountered the P0456 code on my 21 ST with 68k mileage.

It is the only code.. popped up once.. cleared it and it came back on this morning.

I made an appt with my previous employer on Apr 1st to get it checked out but is there anything in the mean time I can check myself? Sounds like possibly a tube off the bottom of the fuel filler neck?

EDWYER · 2026-03-25T07:46:30-0500

MattJ716 said:

Bringing this post up again just because I have encountered the P0456 code on my 21 ST with 68k mileage.

It is the only code.. popped up once.. cleared it and it came back on this morning.

I made an appt with my previous employer on Apr 1st to get it checked out but is there anything in the mean time I can check myself? Sounds like possibly a tube off the bottom of the fuel filler neck?

Check this out.

Mustang5L5 · 2026-03-25T08:34:50-0500

MattJ716 said:

On other vehicles, my "test" was to remove the EVAP purge valve (assuming easily accessible) and simply blow through it. Air should not pass through. If it does, replace the purge valve. Please note, i have not tried this on the explorer valve yet as mine has not failed yet.

Of course if you have other obvious signs of a failed EVAP purge, like not starting after topping off the tank, it's likely the valve.

If it is the valve, it's a $75 part (at this time).

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P0456 Very Small leak

Paulie77

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EDWYER

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SFD295

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MattJ716

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EDWYER

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Mustang5L5

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