neutral safety switch is usually next to the shifter on transmission, it has a electric plug on it , to show ecu it is in park and safe to start car engine, , if bad it wont let you start the car in park or neutral, it should not prevent shifting, but it is a subaru - test neutral switch by turning car to on, but not start, and move to neutral, and then try to start ,if it starts in neutral but not park, then switch is bad,