codes p0455, p0498 still, after gas cap & evap valve replaced

[northguest47]

these codes are still showing after both the gas cap and the evap valve assembly replaced. is this for sure nothing to do with the map sensor/intake? these codes have been there consistently, just thinking about solving them while all the other work is being done

[xintersecty]

Have you checked the charcoal canister in the passenger side rear wheel? Maybe you have a leaky pipe or a loose connection. That will give you the same issue.

[AvMan39]

I have had the same problem and some after market gas caps dont work right. I then went to the dealership and got the factory one from them and problem solved. Some of the after market ones from advance auto and autozone just dont work. I had the same problem and someone told me to go to the chevy dealer and get the gas cap and that solved the problem. Something about the afyer market ones just dont work right. Could be not the right pressure or air entering all i know is the one from the dealership worked and it only cost a little more.

[northguest47]

Have you checked the charcoal canister in the passenger side rear wheel? Maybe you have a leaky pipe or a loose connection. That will give you the same issue.

Oh geez, xintersecty, go I ever feel like a goofball!! I have had these codes thrown consistently since way back in 2011, and I have to admit I didn't do the work on the evap canister, a friend did it. We never checked the connection.
Today at my local shop here in brampton ontario we had 'ol sparky up on the hoist chatting and staring at stuff and I brought up the issue of these codes - the mechanic I use here in town showed me the solenoid which is right above the canister. He said he could replace it, and that often the connection fails. He pulled mine out, and inspected it and pulled back the jacketing to see if there was any damage, then pulled on the connector to see if it would fly off. Looks ok to me, he says, and then puts it back on.
The codes have gone away!!! You were right all along, I didn't fully understand your particular post until today. All it was was a loose connection to the soleinoid, it just had to be un-plugged and plugged back in!
Wow, for the first time in around 8 years I have no check engine light. (fingers crossed I'm finding it hard to believe but I'm heading out shortly for another rip around town).
I giving you a very belated thanks on this one!!

[northguest47]

Never got a response on this one its likely xintersecty like most on this forum will sparsely log in seeing that the car is becoming a fossil. A followup to my previous posts, the code has been thrown again, so my educated conclusion is that the connector needs to be re-connected. Of course the whole piece will be cheaper than the connector though, I wonder. Well see, this will be tested in a few months when the car is up on a hoist.