a while ago my '07 987 CS threw the same code (evap valve..?) and JFP suggested back-blowing air through the valve while applying 12V to the valve connector (to open the valve).
I disconnected the small tube that connects to the throttle body to the valve and blew air through it and the code never returned, you may want to try it.
The Evap valve its located underneath the driver side intake plenum.
a while ago my '07 987 CS threw the same code (evap valve..?) and JFP suggested back-blowing air through the valve while applying 12V to the valve connector (to open the valve).
I disconnected the small tube that connects to the throttle body to the valve and blew air through it and the code never returned, you may want to try it.
The Evap valve its located underneath the driver side intake plenum.
Good luck!
Interesting. I’ll have to find it first. How did you apply 12V?
Saw another post on 453 and it said replace sensor on top of gas tank.