WHAT IS OBD?
On-Board Diagnostics - First Generation (OBD1)
With the exception of some 1994 and 1995 vehicles, most vehicles from 1982 to 1995 are equipped with some type of first generation On-Board Diagnostics.
Beginning in 1988, California¡¯s Air Resources Board (CARB), and later the Environmental Protection Agency (EPA) required vehicle manufacturers to include a self-diagnostic program in their on-board computers. The program would be capable of identifying emissions-related faults in a system. The first generation of Onboard Diagnostics came to be known as OBD1.
OBD1 is a set of self-testing and diagnostic instructions programmed into the vehicle¡¯s on-board computer. The programs are specifically designed to detect failures in the sensors, actuators, switches and wiring of the various vehicle emissions-related systems. If the computer detects a failure in any of these components or systems, it lights an indicator on the dashboard to alert the driver. The indicator lights only when an emissions-related problem is detected.
The computer also assigns a numeric code for each specific problem that it detects, and stores these codes in its memory for later retrieval. These codes can be retrieved from the computer¡¯s memory with the use of a ¡°Code Reader¡± or a ¡°Scan Tool.¡±
On-Board Diagnostics - Second Generation (OBD2)
The OBD2 System is an enhancement of the OBD1 System.
In addition to performing all the functions of the OBD1 System, the OBD2 System has been enhanced with new Diagnostic Programs. These programs closely monitor the functions of various emissions-related components and systems (as well as other systems) and make this information readily available (with the proper equipment) to the technician for evaluation.
The California Air Resources Board (CARB) conducted studies on OBD1 equipped vehicles. The information that was gathered from these studies showed the following:
To address the problems made evident by this study, CARB and the EPA passed new laws and standardization requirements. These laws required that vehicle manufacturers to equip their new vehicles with devices capable of meeting all of the new emissions standards and regulations. It was also decided that an enhanced on-board diagnostic system, capable of addressing all of these problems, was needed. This new system is known as ¡°On-Board Diagnostics Generation Two (OBD2).¡± The primary objective of the OBD2 system is to comply with the latest regulations and emissions standards established by CARB and the EPA.
Objectives of OBD2
The Main Objectives of the OBD2 System are: