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On-Board Diagnostics (OBD)

OBD Logo Vehicle Owners

Do you drive a 1996 or newer car or light truck? If so, it is equipped with OBD—an advanced "on-board" computer system responsible for monitoring your vehicle's engine, transmission, and emissions control components. If your "Check Engine" light comes on and stays on, your OBD system is telling you that it has detected a problem with your vehicle. In addition to protecting the environment, this light, and the OBD system behind it, can save you time and money by identifying minor problems before they become major repair bills.

OBD also plays a key role in nearly 30 state and local vehicle emissions testing programs around the country. In these areas, technicians use OBD checks to identify vehicles that are in need of repair and therefore are exceeding emissions standards. As a result, OBD serves as an important tool in improving air quality and helping states meet national air quality standards.

Use the links below to learn more about OBD and its benefits to you:

This page is maintained by EPA's Office of Transportation and Air Quality (OTAQ).
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