The letter P of the car engine P2122 Code is powertrain and it is an important thing. Rest of the parts of the car engine code has meaning and for the automobile engineer, it is necessary to know all meaning of the code. An automobile engineer will use right meaning of the code and some machines/tools for checking and solving the car engine problem. Do not engage anyone to fix the car engine issue. You must allow a person to solve the car engine problem who knows well how to fix the car engine and how to find the right meaning of the code for solving the car engine.