I have had intermittent check engine light throwing a P1423. I have searched this forum and others and I've seen posts where they indicate it is the passenger side. The dealer (not Audi) I got it from has a contact at an Audi dealer and got me a valve for the driver's side and said his buddy indicated the code is for that side. Can someone confirm? It seems like the only difference is how the mounting flange is lined up in relation to the vacuum port and tube going into the valve. The dealer I got the car from is about 2 hours away so he mailed me the part. I'm not sure if local dealer will swap out the part for the passenger's side so is it possible to use the one I got on the passenger's side and make the connections work?