The US Environmental Protection Agency (EPA) has finalized regulations for onboard diagnostic systems on 2010 and later heavy-duty engines used in highway applications (HDOBD). Although the EPA has not estimated new emissions reductions associated with this HDOBD rule, it considers OBD to be a critical element to an overall emissions control program. As such, it assumed OBD requirements and their associated benefits in the estimated emissions reductions associated with the 2007 highway rule.
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. Also, manufacturers are required 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. Specifically:
For 2010 and later model year heavy-duty diesel and gasoline engines used in highway applications over 14,000 pounds, all major emissions control systems be monitored and malfunctions be detected prior to emissions exceeding a set of emissions thresholds. The aftertreatment devices that will be used on highway diesel engines to comply with the 2010 emissions standards will be monitored and their failure will be detected and noted to the driver. All emission-related electronic sensors and actuators be monitored for proper operation.
For these highway applications over 14,000 pounds, 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 would have to be certified to the OBD requirements. This phase-in is designed to spread over a number of years the development effort required of industry and to provide industry with a learning period prior to implementing the complex OBD requirements on 100% of their highway product line.
For applications over 14,000 pounds, the service information availability requirements would apply for those engines certified to the OBD requirements.
For 2010 and later model year highway heavy-duty diesel applications under 14,000 pounds, the EPA is promulgating a new emissions threshold for monitoring of the diesel particulate filter. The existing requirement for these applications is to detect a catastrophic failure of the device; the EPA said that a more stringent requirement is appropriate and feasible. The emission threshold is consistent, both in stringency and in timing, with the particulate matter (PM) thresholds for over 14,000 pound applications.
For 2007 and later model year diesel highway heavy-duty applications under 14,000 pounds, the EPA is changing the emission thresholds for NOx emissions. The existing thresholds, typically 1.5 times the applicable NOx standard, were established when the engine’s NOx standard (i.e., the 2004 NOx standard) was much higher than today’s very low level (i.e., the 2010 NOx standard). The EPA said that these OBD thresholds are not technologically feasible in the context of the very stringent NOx emission standard, and this change addresses that issue.
In October 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.
In September 2008, EPA granted a waiver from federal preemption to the State of California, allowing it to implement/establish heavy-duty onboard diagnostic (HDOBD) requirements. The EPA said that it worked closely with California on the proposed rule and with both California and industry stakeholders on this final rule, in an effort to develop a consistent, national set of HDOBD requirements. As a result, the new HDOBD program is consistent with the California program in almost all important aspects. EPA said that while minor differences exist between these requirements and the California requirements, the industry will end up with OBD systems that will be compliant with both the federal program and the California program.
The EPA projects that the OBD requirements will result in an increased hardware cost of roughly $60 per diesel engine and $70 per gasoline engine used in applications over 14,000 pounds. It projects that the new requirements for diesel heavy-duty applications under 14,000 pounds will have no increased hardware cost since these engines and vehicles have complied with OBD requirements since 2004.