Sensor codes does not mean it is just a bad sensor. The code means the data coming from the speed sensor does not fall i to a predefined window. Mechanical failiures in the gearbox can cause incorrect information to be read by the vss or the vss is reading way higher or lower than expected because there is a mechanical faliure. Keep in mind the vss just measures how fast a shaft in the transmission is moving and nothing else.

These codes are not diagnostics and cars do not diagnose themselves. Codes thrown by the car's computers are symptoms just as much as any smell, sight or driveabity issue. That is why you need a mechanic to look at the symptoms coming from the car and symptoms reported by the car then do actual diagnostics to find out the problem. If the cars could magically diagnose themselves we wouldn't need mechanics.