You need to know the right meaning of the car engine P1621 Code if you want to fix the car engine. The car engine should be solved properly and this problem is easy to fix. Because the problem is related with the powertrain and it is not necessary to change any part of the car engine. You do not need to add anything with the car engine. The engine code’s meaning is an important but it needs to solve. However, do not try to solve the car engine by any unknown person. However, this problem can be fixed by an automobile engineer.