2007 Cadillac DTS

[DaveDave4228]

Replaced the canister vent valve solenoid and the code is still there. Could it just be a bad gas cap?

[Logan]

What code are you getting? 

The evap vent and purge valves seem to becoming a new GM standard issue. I've had to replace several 'no code' ones on different GM cars. 

You likely need a scan tool to clear the code after the part is replaced to remove the code right away. If not you would need several drive cycles for the SES light to turn off.  

Have seen a leaking gas cap cause evap codes too. 

[rockfangd]

They have been unfortunately for awhile now. At least here in salt country.

Aluminum, heat, and moisture dont go together well.

I would be checking the purge valves and actually first have it smoke tested

[Logan]

I think adding to the problem is there are 2 very similar named solenoids. 

There is a:

EVAP purge solenoid. (Located under the hood) p0443.

EVAP vent solenoid (Located on the evap cansister or on some other cars on the gas tank) p0449.

 

The underhood ones (for me) seem to be more problematic than the gas tank ones. Have seen several cause a 'no code, no start after fill up issue'. Could get the issue to move to an identical car by swapping the evap purge sensor.