Silverado PO449 Check Engine Help!!

Dave Wybierala · November 17, 2016

Hello all!

Im new to the whole forum thing but at this point, ive become desperate. I have a 2008 silverado 2500hd gasser. i bought the truck maybe a year and a half ago and it has had a check engine light since the day i bought it, never really bothered me much and i just cleared the code temporarily to get it inspected in NJ. the problem hasn't become any worse. its just now becoming more and more of a hassle as the weather cools down.

I have the code PO449

the truck also leaks a good amount of gas when you fill it up. maybe a cup? it leaks from the top of the tank and runs down both sides of the tank

Ive read up on the code and many people blame either the gas cap, or the purge solenoid, or the evap valve or something like that.

i replaced this part

http://www.partsgeek.com/vrwkl6g-chevrolet-silverado-1500-vapor-canister-vent-solenoid.html?utm_source=nextag&utm_medium=pf&utm_content=dc&utm_campaign=PartsGeek+Nextag&fp=pp&utm_term=Chevrolet+Vapor+Canister+Vent+Solenoid

in doing so, i ripped one of the lines going into the canister. the leak continued so i tried to RTV the hole that was caused, seemed to adhere just fine.

(Let me also mention, the truck was totaled before i bought it and then was reconstructed. rear end accident. everything looks good now but I'm sure thats what caused this whole thing)

so the Vapor Canister Vent Solonoid didn't fix the issue. i then decided i should try to lift the bed and look at the top of the tank, maybe find where this is coming from. the nuts that are welded onto the frame that the bed then bolts to are rusted and one snapped off, so for now, getting the bed off is kinda out of the question. i have to freeze frame shots of my system from when the Check engine light was triggered. please take a look and help me if you can, id really appreciate any help at this point.

Thank you do much

kstruckcountry · November 17, 2016

If you can't get the bed off, you're going to have to drop the tank. It sounds like that's where the issue is.

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Dave Wybierala · November 17, 2016

Thanks. But any idea what it could be?

davester · November 17, 2016

you might have to cut off the bed bolts, then properly remove the remaining bolt bits from the bed once it's off.

the top of the fuel pump could be rusted out (one of them was on my truck), or one of the fill ports/hoses could be cut/broken.

With either the bed off or the tank dropped, also take a look at the brake line running along the frame (I believe it still runs along the frame above the tank so you can't see it normally) for rust.

Dave Wybierala · November 17, 2016

i appreciate your help Davester, did yours produce a code when you had this issue?

SpartanAutoworx · November 17, 2016

Vent Valve needs replaced. Easy and cheap. Common on the gm trucks you can try and blow it out first but I would just replace.

SpartanAutoworx · November 17, 2016

Also dont overfill the tank when its hot. IMHO that causes the vent valve to go bad pretty quick. But thats just my opinion.

kstruckcountry · November 17, 2016

Vent Valve needs replaced. Easy and cheap. Common on the gm trucks you can try and blow it out first but I would just replace.

The vent valve won't cause fuel to leak from the top of the fuel tank.... Definitely a different issue.

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SpartanAutoworx · November 18, 2016

The vent valve won't cause fuel to leak from the top of the fuel tank.... Definitely a different issue.

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The code is definitely the purge valve.

As for the leak if its only a cup has to be a loose hose or leaky fitting.

SpartanAutoworx · November 18, 2016

Check this out for replacement of the vent valve

http://www.gm-trucks.com/forums/topic/186536-how-to-replace-evaporative-emission-vent-valve-solenoid-for-gmt900/

davester · November 18, 2016

i appreciate your help Davester, did yours produce a code when you had this issue?

There wasn't a code specifically for this (now that the truck is all fixed up, it throws a code for when the fuel cap is not tight [and I don't know the specific code that comes up for this, just that the DIC reports a fuel cap is loose]).

But just given the age of your truck and that it was in a rear-end accident, I would be leaning more towards a broken fitting or cut hose around the fuel tank.

kstruckcountry · November 18, 2016

The code is definitely the purge valve.

As for the leak if its only a cup has to be a loose hose or leaky fitting.

P0449 can be a leak or vacuum loss as well. Considering the truck is dripping fuel, there's a good chance a leak is the issue.

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Dave Wybierala · November 22, 2016

Thank you guys so much for your help. I haven't fixed the issue yet but I think I'm going to start with trying to get the bed off. A little more effort than I put in before. Appreciate it