P0403 is a code I have never seen on a Porsche
. Are you sure?
Ultimately it is your car and your dough but if it was my dough I would verify the code, get a description of the fault involved and use the process of elimination to find and fix the problem. There are good online resources to help. If you are not comfortable doing this it might be money well spent to take your car to a qualified Porsche tech for a diagnosis. Otherwise you could blindly change out $2000 in parts and miss the problem completely... or end up with more error codes
. It happens.