The B1981 Code defines the engine problem from the car engine and it is necessary to fix the problem from the car engine if you want to drive the car without any trouble. You need to know how to fix the car engine problem and necessary information what helps to solve the car engine problem. You can use the dictionary meaning for this code but it does not help you a lot. By the real information and machines, you can solve the problem from the car engine. The dictionary meaning for the code is available online and general meaning can be known from the dictionary meaning.