The vent is supposed to be Normally Open so that no vapor lock should occur. Sounds like the canister vent solenoid is stuck closed (like the code suggests). I suspect that filling the tank is PIA; start/stop.

You don't need the adapter unless it is a 2006-2007.

 

I've been chasing the P0499 code for 5 years changed the solenoid 3 times! Each time the code went away for about 500 miles. But anyways came back. Recently my HHR was in a shop for a different issue and I was telling the guy about the code. He asked if I ever changed the charcoal canister next to the solenoid. Of course I hadn't, the code is the solenoid! He told me change both and the code will go away. Got the charcoal canister changed the other day and will do the solenoid hopefully this weekend. Praying!

 

Have you considered looking at the purge vapor line for corrosion?

 

The mechanic was the one pointed out that it's charcoal canister giving problems and said that the purge valve was fine. Went to replace the solenoid today and broke my harness wire. 😡 I'm not spending $76 for an ACDelco harness. That's $20 more than the solenoid. I'll just get a cheap aftermarket and pay it all works when I get it on. Or, to the junkyard I go.

 

I did not mean the purge VALVE, the vapor LINE that runs parallel to the fuel line is prone to rusting out under the insulation in front of the driver side rear wheel.
If your car is a 2006 a pigtail is required and is widely available, some valves come with one.

 

Read carefully these instructions, particularly #5 from the way back machine, Sherman found!

https://www.chevyhhr.net/forums/how-...acement-44780/