The engine P21B0 Code explains the problem of the engine and it has two different meanings. One meaning is general/automobile dictionary based and another is manufacturer based. Do not use the automobile dictionary meaning for solving the car engine. The problem from the car engine is not easy to solve but the problem from the engine can be solved easily. This engine code is the area code of the engine and based on this, the problem of the car engine can be solved. Do not drive the car with any type of problem. It may bring more serious problem in your life.