Got you. I ordered 3 of them from suncoast along with the wiring harness for a little less than $300. I’ll see what happens when I replace them. Hopefully a dealership will be willing to reset my light and I guess if it pops back up I’ll have them figure out which of the 5 other ones are faulty since I don’t really have the time to dig around under the car right now.

 

My 2015 C2 appears to only have 7, even though it's a PDK car. I found the two under the car; one is easy to do, one is under the driver's side transaxle and a total PITA to get to. Then there are the two on the airbox, the one on the right wall in the rear, and supposedly three more to the right of the engine. I could only find 2 to the right of the engine; I found a third mounting spot (for #6 in the Plenum blogpost, for "tuning flap"), but it's empty. I traced the vacuum and fresh air lines all over - no eighth valve that I could find.

Maybe the S models have one more than the base Carrera? Or maybe there's just one so hidden I couldn't find it. Not sure.