Got a Check engine light day after i bought car week ago. I put gas in the day i bought it and all was fine. Next day i changed oil and light came on.

Had it scanned with OBDII and came back with emissions leak. Changed the gas cap and reset computer. Code was gone till today and came back. Havent added fuel since the first time.

What else or could say be the cause of it, hard to look under for me to see if the EVAP system has any cut in the hoses or what not. Car drives fine so woudlnt know it was that.

2005 monte carlo

 

do you remember what the exact code was?

 

Not exact numbers or anything, But said Emissions Leak purge no flow....

 

Possibly P0455

The most common problem is the gas-cap, so good job replacing that. You might have to get the system checked out though to find where the leak is.

Could be a tube that has a slit, or something else simple.

 

Someone will have to help me with a formal name. I had a similar code and fixed it by replacing a valve. It's right next to the gas tank filler neck. It lets you vent off air when you fill the tank, it also lets you vent when running so you don't build up pressure.

Any help with the proper name? Changing this piece fixed my evap code.

 

is this sorta behind and below the filler neck ? plastic round feeling thing maybe?
I am having the same issue as the OP , so very interested in a possible fix.

Mine is throwing off code 455

 

Mines the same code P0455. Its the Purge Valve right at the top of the neck of the gas cap. Look under the car and follow the tubing up and youll see a canister there.

Its a 45$ dealer part and easy to install.

 

I had the smoke test done today to make sure, yeah it is the purge valve the GM mechanic said it was a extremly common thing for w bodies . I am guessing thats our montes and the four door version called the impala. btw I checked around and got the AC Delco part for $27 at advanced auto . I also found a step by step with pictures walk thru at LS4 forum.
credit goes to the OP of course.
HOW TO:Replacing Evaporative Emission Canister Vent Solenoid Valve (PO455 error)

 

ok so I just finished swapping the evap purge whatever, the how to I linked is good but you do NOT have to remove the tire or splash gaurd. I just posistioned myself behind the drivers rear tire used a 10 mm socket and unbolted the bracket. The entire process took MAYBE 20 minutes start to finish.