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Discussion Starter · #1 ·
I have a 2011 Silverado 5.3 liter, and have a check engine light on due to a PO442-small EVAP leak. I have replaced the EVAP vent control solenoid, and the purge valve. I purchased a smoke machine, used that tonight and cannot see any leaks in the system. The only place it was showing smoke was the line coming from the EVAP vent valve solenoid to the fuel filler cap, I believe that is normal considering the truck is off, and the EVAP vent valve shuts when the truck checks its system correct? As I said that vent valve is brand new lines and all. I disconnected that line on the charcoal canister and checked the system. There was no smoke coming from anywhere that I saw, and I tried smoking it multiple times to be sure. So my question is where to go from here. Is it the charcoal canister? The fuel tank pressure sensor? In the system those are kind of what I’m down to considering I saw no actual leaks? Just curious what anyones thoughts are who might have any with this annoying insignificant issue that keep illuminating my check engine light.
 

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2003 Silverado 1500 LS
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Try a new fuel filler cap. Not 100% guaranteed that's what it is, but 'often' that's the cure. Also, when you fill fuel tank, don't overfill. I have a pristine 2010 Cadillac DTS that throws the same code, but only if I fill the fuel tank really full. So now I stop at the first click of the auto-stop on the fill handle.... or if I hear it getting full.
 

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Discussion Starter · #5 ·
Sorry, I didn’t mention in the original post, the fuel cap is the first thing I replaced. And when I smoked it there was no smoke coming from around it, so I know the current cap is good. I usually always stop on the first click when filling my tank. But I do wonder if the fuel cap/filling it may be the issue. I can clear the code and it’ll stay off for a good month+ without coming back on.
 

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If you can clear the code and it stays off, I'm guessing it was overfilled a bit, and spilled into the line to be purged out as normal. The system also only checks and runs the test when your tank is below 3/4 full...I used that to get a sticker on my 2006 a few times...just kept it filled up for a week before test time, because in MA they check for last system reset and if too close to test day it's an auto-fail, or they reject the test and tell you come back. My issue was, er...is, I have a moderate separation on top of the gas tank where the pump sits...probably got cracked/opened when one of the tank straps rotted out and tank dropped down a few inches...lol

Lucky for me, truck is now old enough they only check basic safety crap...
 
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