The History of On-Board Diagnostics

HISTORY OF OBD

By: x240xdrifter

In the early ‘60s, the state of California mandated laws that required emission control systems to be in cars to help reduce the smog problem. Once the Government caught word of this, they expanded the idea so the whole country would have to require OBD (on-board diagnostics) by 1968. Since then the future of vehicle repair has changed for the better.

As the American public began to realize that it was time to set standards in aspiration to help the environment, Congress passed the first Clean Air Act in 1970 which was the foundation of the Environmental Protection Agency (EPA). In the following decades, the EPA began to set the baseline for emissions. For example, the EPA required all cars to have catalytic converter by 1975. Most automotive manufacturers started to install computer systems and data-logging sensors to help control the emissions. In aid to these systems, manufacturers also introduced electronically controlled fuel injection and ignition systems. These systems were introduced to help maximize engine efficiency and performance while maintaining minimum emissions.

In 1982, the EPA required that all cars to be produced with engine monitoring systems. These systems were used to monitor the engine controls and sensors. If a problem is picked up by the monitoring system, a check engine light within the dash would illuminate. A benefit of this system is that auto manufacturers could constitute their own communications guidelines and error code definitions. A common way to retrieve these codes was to count the number of blinks the check engine light made.

On-board diagnostics (OBD) was introduced in 1985. OBD was formulated to revolutionize the monitoring systems used beforehand. Eventually most cars and light trucks were equipped with this new system by 1988. The Society of Automotive Engineers (SAE) designed a standard connector plug also know as a Data Link Connector as well a set of test signals to go along with the system. The EPA applied this new technology to make the servicing of the vehicles easier.

In 1996, SAE introduced their second generation of On-Board Diagnostics, formally known as OBD-II. The goal of the new system was to have new error codes known as Diagnostic Trouble Codes (DTC) that would be universal to all vehicles. These codes were also designed to be read by any OBD-II scan tool. The codes start with one letter and four numbers, for example P7890. Manufacturers were also allowed to add their own codes pertaining to their own models on top of the required ones. This system was soon adopted by the Government which required all vehicles to be manufactured with OBD-II beginning January 1st, 1996.

On Board Diagnostics has come a long way since the idea was contemplated back in the early 1960’s. It’s amazing to see how a small idea that initially only pertained to California State laws all because of the smog issue grew into a nationwide requirement. The OBD system is great because it has proven over time how valuable it is not only to the environment but to the technicians as well. This system has greatly reduced emissions and diagnostic time.