The U.S. Environmental Protection Agency issued final rules requiring on-board diagnostic systems on heavy-duty vehicles to monitor emission control systems.


On-board diagnostic systems, or OBD, have been required on passenger cars since the mid-1990s to monitor emission control systems and detect malfunctions. The system alerts the driver of the problem, enabling a service technician to diagnose and properly repair the problem. Now they will be required on 2010 and later heavy-duty engines used in highway applications over 14,000 pounds.

In addition to these requirements, EPA is requiring manufacturers to make available to the service and repair industry information necessary to perform repair and maintenance service on OBD systems and other emission-related engine components.

This rule also makes changes to certain existing OBD requirements for smaller highway heavy-duty diesel trucks.

The rule requires manufacturers to install OBD systems that monitor the functioning of emission control components and alert the vehicle operator to any detected need for emission-related repair. In addition, when a malfunction occurs, diagnostic information must be stored in the engine's computer to assist in diagnosis and repair of the malfunction. The aftertreatment devices - e.g., the diesel particulate filters and oxides of nitrogen (NOx) reducing catalysts - that will be used on highway diesel engines to comply with the 2010 emissions standards must also be monitored and their failure detected and noted to the driver.

There is a phase-in aspect to the regulation. EPA is requiring that one engine family per manufacturer be certified to the OBD requirements in the 2010 through 2012 model years. Beginning in 2013, all highway engines for all manufacturers will have to be certified to the OBD requirements.

The final rule is a major step in EPA's efforts to work with the California Air Resources Board to develop a consistent national heavy-duty OBD program. EPA's new heavy-duty OBD program is consistent with the California program in almost all important aspects, according to the agency.