OBD or On-Board-Diagnostics have been around since 1980, when General Motors first introduce the system in certain vehicles sold in California, Chrysler and Ford soon followed. By the mid 1980's the Asian and European manufactures were installing on-board computer systems for the purpose of controlling emissions. With the increasing smog problem nationwide every light duty vehicle sold in California in 1988 had to comply with the new OBD-I (first generation) regulations. The intent was to gain consistency on the way emission systems were being monitored and how emissions problems could be brought to a driver's attention.
The OBD-I regulations for 1988 required onboard computer systems have the ability record and store a specific diagnostic trouble codes for a malfunctioning sensors or systems. The major requirement of OBD-I was to notify the driver of malfunction by having the on-board computer turn on the MIL or Malfunction Indicator Lamp more commonly known as the "Check Engine" or "Service Engine Soon" light.
The 1990 Clean Air Act Amendments adopted the new OBD-II (second generation) requirements. These new requirements were implemented for every vehicle sold in the U.S starting in model year 1996, which included the following:
- The use of the same universal Diagnostic Link Connector in every light-duty vehicle sold in the U.S.
- A standard location for the Diagnostic Link Connector
- A standard list of Diagnostic Trouble Codes (DTC)
- Common diagnostic test modes
- The ability to record a snapshot
- The ability to store a code when an emissions failure occurs
- A standard glossary of terms