The Air Resources Board (the Board or ARB) will conduct a public meeting at the time and place noted below to consider ARB staff’s update on the status of efforts to reduce in-use NOx emissions from on-road heavy-duty diesel vehicles. This item addresses element M17 of the California State Implementation Plan (SIP), is informational only, and no regulatory action will be taken.

DATE: January 31, 2003

TIME: 9:00 a.m.

PLACE: Air Resources Board

Central Valley Auditorium

1001 I Street

Sacramento, California 95814

This facility is accessible to persons with disabilities. If accommodation is needed, please contact ARB’s Clerk of the Board at (916) 322-5594 by January 21, 2003, to ensure accommodation. Persons with hearing or speech impairments can contact us by using our Telephone Device for the Deaf (TDD) at (916) 324-9531, or (800) 700-8326 for TDD calls from outside the Sacramento area.


Reductions in mobile source emissions are essential to the attainment of the federal and state ozone air quality standards. Diesel engines used in heavy-duty on-road vehicles and off-road equipment are the largest source of ozone-forming nitrogen oxide (NOx) emissions. The 1994 State Implementation Plan (SIP) for ozone identified several approaches to reduce NOx and other emissions from heavy-duty on-road diesel vehicles. One approach is to adopt more stringent emission standards for new heavy-duty diesel engines used in on-road vehicles. Since approval of the SIP, the Board has twice adopted more stringent emission standards which will result in a 50 percent reduction in NOx emissions of 2004 models, and another 90 percent reduction in both NOx and particulate matter (PM) emissions of 2007 models.

Another approach is to reduce emissions from the fleet of heavy-duty diesel vehicles already on the road. On-road vehicles may have elevated emissions due to malmaintenance, defective parts or an emission control system design which is not durable. One SIP measure, M17, called for developing a new, in-use program to address the excess emissions of on-road heavy-duty diesel vehicles. This program could include a new field test to screen heavy-duty on-road vehicles that have high NOx emissions, and require their repair. It could also include a testing and recall program similar to that currently in place for light-duty vehicles. Such a program could identify engines whose emission control systems lack in-use durability, and require recall and installation of more durable parts. The program could also require the installation of on-board diagnostics (OBD) on new heavy-duty diesel engines. OBD can identify individual emission control parts and systems that have failed or are not operating properly. In combination with other programs, repair of the defective parts or systems could be assured. Finally, ARB agreed to pursue financial incentives for advanced heavy-duty technologies capable of emissions below the required standards for new engines.

The program is to be adopted by the Board by January 2004, and is to achieve emission reductions of ten tons per day NOx, and one ton per day reactive organic gases (ROG), by 2010. The proposed items will discuss potential ways to address this concern

Summary of Presentation

Staff will present to the Board a progress report on efforts to develop a program to reduce in-use NOx emissions from on-road heavy-duty diesel vehicles. The elements of the program being evaluated are: 1) a field testing program to identify on-road heavy-duty diesel vehicles with excessive NOx emissions that would complement the current ARB program that inspects for visible smoke emissions; 2) an in-use compliance program that tests specific engine models to determine if their emission control devices and systems have remained effective during the vehicles’ useful life; and 3) a regulatory requirement that new diesel engines used in heavy-duty on-road vehicles be equipped with an OBD system that provides a real time assessment of each emission control device or system and warns the operator when a defect or malfunction has occurred.

for implementation in 2007, the efforts to date on the development of a NOx reduction inspection and maintenance program, and current outstanding issues, For more than a year, staffs havehas been testing and repairing heavy-duty diesel trucks in an effort to determine whether significant NOx reductions can be achieved by adding a field test for NOx to the current smoke inspection program. The testing and evaluation is designed to quantify the excess NOx emissions from the current in-use fleet of heavy-duty diesel vehicles, determine if a field screening test can accurately identify the higher emitters, and assess the effectiveness and cost of emission-reducing repairs. Staff will present the results of the study and discuss the feasibility of implementing a field inspection program for NOx.


In March of 2002, ARB staff began working with the U.S. Environmental Protection Agency (EPA), engine manufacturers association (EMA), and diesel engine manufacturers to develop a manufacturer-run, in-use compliance program. In this proposed program, the engine manufacturer would test engines of the same model to determine if they are in compliance with the emission standards to which they were designed. If high emissions and a defective design are identified, the manufacturer would recall all trucks using that engine, and modify them to comply with the emission standards. ARB may also test engines and order a recall if appropriate. Critical to this program are the Not To Exceed (NTE) test procedures previously adopted by the Board, which allow a simplified method of determining in-use compliance. The ARB and EPA staff, and EMA, are close to reaching concensus on how such a program could be implemented. We will be proposing regulations to implement this program later this year. The program would begin as a pilot in California for the 2005 and 2006 model years, and would become fully enforceable with the 2007 model year. U.S. EPA also intends to adopt this in-use compliance program effective with the 2007 models.

Staff is also developing a proposed regulation that would require new diesel engines used in heavy-duty trucks to be equipped with an OBD system, beginning with the 2007 models. Additionally, for more than a year, Mobile Source Operations Division staff have been testing and repairing heavy-duty diesel trucks in an effort to determine whether significant NOx reductions can be achieved through a Smog Check type program. More test data is necessary to render an informed decision regarding this effort.

OBD systems are comprised mostly of software in the on-board computer that monitors virtually all emission-related components for malfunctions. When a malfunction occurs, the OBD system alerts the driver by illuminating a dashboard warning light, and stores diagnostic information that can be retrieved by repair technicians to identify the likely cause of the malfunction. The OBD system can be used during field inspections to screen out those vehicles in need for repair. It can also be used to identify engines models with high failure rates of emission control parts, resulting in compliance testing and a possible recall. OBD systems have been currently required on all gasoline and light and medium duty diesel vehicles since the 1996 model year, and have proved to be highly effective. The ARB staff plans to bring an OBD regulation for heavy-duty vehicles to the Board for consideration later this year.

Availability of Documents and Agency Contact Person

Copies of the presentation prepared by staff may be obtained from the Board's Public Information Office, 1001 "I" Street, 1st Floor, Environmental Services Center,

Sacramento, CA 95814, (916) 322-2990. The presentation may also be obtained electronically from the ARB internet site /msprog/onroadhd/hdiut.htm

To obtain these documents in an alternate format, please contact the Air Resources Board ADA Coordinator at (916) 323-4916, TDD (916) 324-9531, or (800) 700-8326 for TDD calls from outside the Sacramento area.

Further inquiries regarding this matter should be directed to Mr. Stephan Lemieux, Manager, On-Road Heavy-Duty Diesel Section, at (626) 450-6162, or, or Mr. Don Chernich, Manager, Heavy-Duty Diesel Inspection and Maintenance Development Section, at (916) 322-7620, or

Submittal of Comments

Interested members of the public may also present comments orally or in writing at the meeting, and in writing or by e-mail before the meeting. To be considered by the Board, written comments not physically submitted at the meeting must be received no later than 12:00 noon, January 30, 2003 and addressed to the following:

Postal mail is to be sent to:

Clerk of the Board

Air Resources Board

1001 "I" Street, 23rd Floor

Sacramento, California 95814


Electronic mail is to be sent to: and received at the ARB no later than 12:00 noon, January 30, 2003.

Facsimile submissions are to be transmitted to the Clerk of the Board at (916) 322-3928 and received at the ARB no later than 12:00 noon, January 30, 2003.

The Board requests, but does not require, 30 copies of any written submission. Also, the ARB requests that written and e-mail statements be filed at least ten days before the meeting so that ARB staff and Board members have additional time to fully consider each comment.

No amendments to the current on-road regulations discussed in this notice will be considered or adopted by the Board at this meeting as part of this agenda item.




Michael P. Kenny

Executive Officer

Date: January 14, 2003
























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