2004 Z71 Ext-Cab 1500 threw a code today. P0455 Evaporative Emission System Leak Detected (gross leak/no flow). Oriellys is who told me the code, per their diagnostic reader. He cleared it, and it hasn't came back on. Is this a big deal? If it is or isn't, what in the hell is that? What can I do to fix it, if the code throws again? Thanks

 

EVAP hose is leaky or plugged or gas cap wasn't fully tightened last fill up

stupid emissions bs

 

Most likely a vent solenoid stuck open. Not a big deal. Easy to replace

 

It did it again, check engine light is back. It runs fine, except at stop lights. When I stop it starts cutting and idles up and down. Idles from about 1700-800, fluctuating back and forth. I will go by oreillys again tomorrow and have them run the code.

 

Solenoid valve on top of intake is probably bad, or you have a broken purge line going to that valve. If you look at the top of the intake near the throttle body (take the lid off) you'll see a black plastic tube going to a cylinder with a 2-wire connector. Pop the hose off, unplug the wire and start the engine. If you've got vacuum at the solenoid nipple, the solenoid is defective. If not...you probably have a broken line or broken charcoal canister in front of the fuel tank.

NOTE: Do not test the lines with an air compressor. None of the fittings, tubing or components are designed for more than 1PSI of pressure. (you can use a smoke machine with a pressure regulator)

 

So I just got home from work and popped my hood. You gotta be kidding me!! SLP CAI had came loose and was about a half inch off. I should have checked for this sooner, because its not the first time its done this. I guess the code reader is what had me looking in the wrong spot. Is it normal for the Oreilly code reader to say " P0455 Evaporative Emission System Leak Detected (gross leak/no flow)" and it turns out the air intake is where the problem was at? I'll take it back to them tomorrow to clear the code, again!

 

I think you have two separate issues at play. Sure, the intake coming off could make a 0455 set and would make the truck run poorly, but the manifold vacuum is not dependent on the intake pipe being seated (as the throttle blade angle/rpm controls vacuum). What 0455 means in that the fuel tank failed to see a vacuum for some reason.

The CAI slipping off should have thrown lean codes 0171 and 0174.

 

When I filled up a couple of days ago (I think a day or 2 after the initial light), I went to open my gas cap and it wouldn't turn. So, I just pulled it, and it came out. It isn't malfunctioned, I think the plastic hanger on the cap was binded up. Which led me to think it was tightened. I had filled up 1 day before the initial light. Thanks for the help guys! Problem solved for now.