Dictionary of Technical Terms
"A" "B" "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
"N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"

Onboard Diagnostics History

Background of the OBD interface from the EPA, with filings and rule numbers removed for ease of reading.

Check Engine Soon

On-board diagnostic systems (OBD) were developed in the 1980s to help technicians diagnose and service the computerized engine systems of modern vehicles. but there was no standardization or requirements for the interface.

Staring in 1987 California required an OBD type interface on all 1988 and newer vehicles

The 1990 Clean Air Act [CAA] required a computer-based early warning system [OBD] to come standard on all Model Years 1996 and newer light-duty cars and trucks. The CAA also required that checks of the on-board diagnostic (OBD) system be included in all mandatory Inspection and Maintenance [I/M] programs to help ensure that vehicle owners take this early warning seriously. This became effective in 1996, but not all states have an inspection plan.

Staring in 1991 California required OBD on all 1991 and newer vehicles

Beginning in February 19, 1993, EPA published a final rule requiring manufacturers of light-duty applications [cars and trucks] to install OBD systems on their vehicles beginning with the 1994 model year. The OBD systems must monitor emission control components for any malfunction or deterioration that could cause exceedance of certain emission thresholds. The regulation also required that the driver be notified of any need for repair via a dashboard light, or malfunction indicator light (MIL), when the diagnostic system detected a problem [check Engine Light].

On August 9, 1995, EPA published a final rule that established service information regulations for light-duty vehicles and light-duty trucks . These regulations, in part, required each Original Equipment Manufacturer (OEM) to list all of its emission-related service and repair information on a Web site and note how to obtain that information and at what cost. The intent being to ensure that after-market service and repair facilities have access to the same emission-related service information, in the same or similar manner, as that provided by OEMs to their franchised dealerships. These service information availability requirements have since been revised.

1996; All 1996 and newer gasoline and alternate fuel passenger cars and trucks are required to have OBD systems [1990 CAA]. All 1997 and newer diesel fueled passenger cars and trucks are also required to meet the OBD requirements.
In California all 1996 and newer gasoline and alternate fuel passenger cars and trucks are required to have OBD-II systems. OBDII systems are more effective because it monitors more of the emission-related components and they are calibrated to a specific level of emission performance.

In October of 2000, EPA published a final rule requiring OBD systems on heavy-duty vehicles and engines up to 14,000 pounds gross vehicle weight rating (GVWR). In that rule, EPA expressed its intention to develop in a future rule OBD requirements for vehicles and engines used in vehicles over 14,000 pounds. EPA again expressed this same intention in its Clean Diesel Trucks and Busses final rule which established new heavy-duty highway emissions standards for 2007 and later model year engines.

On January 18, 2001, EPA established a comprehensive national control program, the Clean Diesel Trucks and Buses program, to regulate the heavy-duty vehicle and its fuel as a single system. As part of this program, new emission standards for heavy-duty highway engines and vehicles began to take effect in model year 2007 and are being phased in through 2010. These standards are based on the use of high-efficiency catalytic exhaust emission control devices or comparably effective advanced technologies.

In June of 2003, EPA published a final rule extending service information availability requirements to heavy-duty vehicles and engines weighing up to 14,000 pounds GVWR. EPA did not extend these requirements to engines above 14,000 pounds GVWR, deciding to wait until such engines were subject to OBD requirements.

In 2008 All vehicles [cars] sold in the United States are required to use the ISO 15765-4 signaling standard.

In 2010, the EPA rules for heavy-duty vehicles and engines weighing up to 14,000 pounds GVWR take effect.

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