2014 Nissan Note: P1715 Error

On a long distance trip, the Nissan Note 2014 I have started acting as though it was not going into the highest gear. Whenever you'd rev it, it would go up and at the time that you'd think it'd shift gear, it revs back down as though you are changing down in a manual car.

Whenever you'd reduce speed to zero, it would have very low revs, sometimes even not responding despite slamming the pedal to the floor.

The engine light came on and the Auto light started flashing (what does this mean? Please help). I scanned the code and it is P1715 input pulley speed sensor which is busted.

I'd love to believe that it is but I am worried about the transmission. Sometimes, it'd not go into the high gears and would have to travel at high RPMs probably in third. And when you come to a complete halt, it surprisingly goes out of gear, which is corrected by throwing the lever into park then going into drive again, but even when you do that, it doesn't rev up.

Could this just be the input pulley speed sensor?