Another p0456

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EastWestHemi

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First got this code two years ago randomly and cleared it with the handheld scanner. Figured I didn’t get the gas cap tight or something. It came back a couple times in the past year, and cleared it.

Three months ago it is now persistent and popping up again every 4-5 cold starts— once a week. Replaced the fuel cap changed nothing. Then I checked over the lines coming from the top of the fuel tank, didn’t see anything wrong. So I went ahead and changed the leak detector, still popping up the same.

I should have just replaced the purge valve from the beginning. Today I tackled the purge valve, took it off, and sure enough I could blow through it. It was hard to blow through it but it definitely was letting air through. Went to the dealership and bought a new one. Tried to blow through the new one and it’s tight as a whistle. Installed and keeping my fingers crossed.

If anyone else is getting the p0456 I’d probably take a look at the gas cap and purge valve first, leave that leak detector module alone— although there is a rubber gasket that seals the leak detector to the evap canister that I suppose could dry and crack.

dealer prices— $55 for purge valve, $95 for leak detector module, and $30 for gas cap. Probably still saved money vs having the dealership do the work and now I have three new parts.

Be patient with the purge valve inlet clips. mine had a red locker clip that was easy to take off, but the little horseshoe white clip that actually holds the line is difficult. I had three little flathead screw drivers to carefully pry it in the right directions to get it out. I was worried that the plastic would be brittle, being my truck is 7 years old, but I got it free without breaking it. I pried the bottom first, and got that started before working in the top.

Just hope it’s not one of the lines that dives down behind the engine…. Time will tell.
 

GTyankee

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Almost always, it is the Purge Valve

I don't know why the trouble shooting guides write Fuel Cap first.

I know that IF it was the fuel cap, it should be replaced with a Mopar Fuel Cap.
After Market Fuel Caps don't always make a good seal
 
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2003F350

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Almost always, it is the Purge Valve

I don't know why the trouble shooting guides write Fuel Cap first.

I know that IF it was the fuel cap, it should be replaced with a Mopar Fuel Cap.
After Market Fuel Caps don't always make a good seal

They call out the fuel cap because it sees the most wear - how many times do you take the cap off to fill your truck? Chances are the gasket went bad. At least that's what their thought was when it was designed.

They likely didn't take into account that the purge valve is likely a sub-par design and fails more often.
 
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EastWestHemi

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Well darn it, replaced the gas cap, purge valve and leak detection valve and code came back again…. Anyone have any thoughts on this one? Crawled under the truck and there are a ton of places where evap lines could rub and as the lines route up and over the transmission who the hell knows. May have to take into a dealer. WTF.
 

GTyankee

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How many times have you started & driven the truck since you swapped out those parts ?
10 or more times ?
 

RAZ175

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You need to hook up a smoke machine to find where the leak is.
 
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