Universal OBD II Concepts: Overview

There is a tendency to view OBD II as monolithic concept which dictates a universal approach to all aspects of emissions controls. The truth of the matter is that manufacturers still have a great deal of freedom in the way they design and build their cars. Each car line and engine family may well require a slightly different solution for any given problem. Don't assume that, just because you understand one OBD II system, you understand them all.

There IS however, a high degree of standardization governing control of the MIL, the setting of fault codes, and of the terminology we must use to describe the process. The next few articles discuss concepts which will be the same no matter whose system you may be working upon.