And what bearing does the tank pressure have on the electronic states of the driver v the coil? I guess if the pressure was over so much that it forced the valve to stay open against a command to close?

Darn near everything that is controlled by a computer has a code associated. A list of OBDII codes can be found pretty easily with GoOgle, I think a list is posted on this site.

 

Yep that's whit I do too, live data monitor to watch the evap system do its thing. Maybe I'll get some time this weekend to get under the car and check out the vent solid thoroughly.

 

I also had a code P0014 so I replaced the cam exhaust solenoid, that took care of the hard shifting. The evap vent solenoid was getting a modulated voltage during the purge cycle. So after all the repairs and checks I still couldn't clear the P0449 & P0014 codes and took the car to the dealer as it was also due for a coolant flush. Their report stated they lubed the seals on the evap system to fix a vacuum leak. So now I'm totally confused.

 

I need to update my last post after re-reading the dealer repair ticket. "Scanned DTCS, had small evap leak, Code P0440, cleaned fuel neck of rust, lubed sealing surface, cleared DTCS, Tested, everything working properly at this time"
My scanner picked up P0014 and P0449 and I did all the repairs/testing as noted above and never could clear the codes and never got a P0440 code. Has anyone heard of code scanner returning incorrect information?

 

Yes, some scanners don't read correctly.

Was the CEL on when you went to the dealer?
Are you talking about "historic"/"permanent" codes you are seeing?

Many of those types of codes take 50 cold start cycles to clear and there will be no CEL.

You need to know what you are looking at when it comes to OBD codes. There is a lot of info on the internet.

 

Yes the CEL was on when going to the dealer, and both codes appeared in the current and history windows. What bothers me is the dealer got the P0440 code and I didn't. It may be as you say, the two codes in this thread were cleared but caught in the cold start buffer because they were emission's codes and I had the CEL still lit from a code my scanner didn't pick up. Kinda pissed as it cost me some money not seeing the P0440 and I would have started at the gas cap on that one. I've contacted the scanner manufacturer but not expecting much from them.

 

The CEL was still on when the dealer released the car??????

 

I had no CEL when the dealer returned the car. The scanner manufacturers comment to my dilemma was "we have no idea why you couldn't see a P0440 code and the GM dealer could". I completed a drive test after I got the car back from the dealer recording the live data for future reference and the evap system was operating as it should. I had checked the gas cap during the original trouble shooting even though I didn't get a P0440 code. I didn't see anything abnormal, the gas cap seal was intact and the seat wasn't damaged. I gotta believe the dealer report is honest as they replaced no parts on the evap system.

 

The 9 and 0 are right next to each other on a keyboard. Could it be a typo?

 

Nope not a typo, checked recorded history in the scanner.