Abstract The world of I.T is taking over everything on this planet and the use of computers in our day to day activity is one of the major achievements of this century. Computer can be used for virtually everything we humans can do and it makes life easy for us. Computer-Aided Troubleshooting in an automobile is the use of computer to help individuals or automobile engineers in detecting faults and providing them with the appropriate solution. This can only be achieved by building an expert system. One of the reasons for this research is to preserve the knowledge of a leading expert in the field of study after his death. Also, this expert system will make junior workers rise to an equal level with the engineers where there are no enough leading engineers.