CALIFORNIA AIR RESOURCES BOARD
Auditorium, First Floor
400 "P" Street
September 12, 1991
91-7-1 Public Hearing to Consider Technical Status Update and
Proposed Revisions to Malfunction and Diagnostic System
Requirements Applicable to 1994 and Subsequent
California Passenger Cars, Light-Duty Trucks, and
Medium-Duty Vehicles - (OBD II).
ITEM NO.: 91-7-1
Public Hearing to Consider Technical Status Update and Proposed
Revisions to Malfunction and Diagnostic System Requirements
Applicable to 1994 and Subsequent California Passenger Cars,
Light-Duty Trucks, and Medium-Duty Vehicles - (OBD II).
The staff recommends that the Board adopt the proposed
modifications to the OBD II requirements (Section 1968.1, Title
13, California Code of Regulations [CCR]), and the updated
reference to Society of Automotive Engineers (SAE) Recommended
Practice (J1930) in Section 1977, Title 13, CCR.
The OBD II requirements were adopted on September 14, 1989. At
that time, the Board directed ARB staff to provide an update in
two years regarding progress of industry towards implementing the
OBD II requirements beginning with the 1994 model year, and to
propose any necessary regulatory modifications.
Staff has met with numerous vehicle and emission control system
manufacturers since the 1989 Board hearing and has held a public
workshop to discuss manufacturers' progress and concerns. The
regulatory modifications proposed are based on information
presented during these meetings and through discussions with the
Environmental Protection Agency (EPA) which is currently
developing a set of federal OBD requirements.
After extensive discussions with industry, ARB staff believes
that the implementation of the OBD II requirements in the current
time frame is feasible. Staff believes that adequate monitoring
strategies exist for all of the monitoring requirements.
ARB staff has worked to address as many manufacturer concerns as
possible. Several changes to the regulations are proposed on
this basis. In other instances, modifications have been proposed
to clarify the intent of the original requirements.
For the catalyst efficiency and evaporative system monitoring
requirements, development efforts by industry and EPA have
yielded monitoring strategies that appear significantly more
effective than those envisioned when the OBD II requirements were
first adopted. In order to keep pace with industry progress, ARB
staff is proposing enhanced monitoring requirements in these
areas. In both cases, additional lead time is provided to
An enhancement to the secondary air monitoring requirement is
proposed that would require manufacturers to correlate the
malfunction criteria for the system with emissions. ARB testing
has shown that the performance of this system will become
increasingly important as emission standards tighten.
Manufacturers that can demonstrate that an air delivery system
leak is unlikely may request Executive Officer approval to
perform only a functional check of the system.
A section has been added to address heated catalyst systems.
Because of the importance of these systems in meeting Low
Emission Vehicle (LEV) standards, manufacturers would be required
to monitor the performance of the heating system and the
conversion efficiency of the catalyst itself.
SAE Recommended Practice J1930 is referenced in the OBD II
regulations (Section 1968.1 of the Title 13) and also in Section
1977 of Title 13. The most recent version of J1930 is referenced
as part of the proposed modifications to the OBD II regulations.
In order to maintain consistency between the two sections, staff
is proposing regulatory language that would update the reference
in Section 1977 as well.
SUMMARY AND IMPACTS
As ARB staff discussed the proposed modifications with
manufacturers, issues arose regarding the amount of lead time
necessary to incorporate the modifications, and the feasibility
of the malfunction criteria requirements of some of the
monitoring strategies for LEV applications. Staff is proposing
regulatory language that it believes addresses both of these
The only additional cost associated with the proposed
modifications results from implementing the enhanced evaporative
system requirements. The cost effectiveness of this requirement
has been determined to be $1.11 per pound of hydrocarbon