California Air Resources Board is proposing a regulation to require
a heavy-duty diesel engine software upgrade for 1993 to 1998 engines.
the 1990s, engine manufacturers used computer-based strategies on
engines in trucks, school buses, urban buses and motor homes that
allowed the engines to comply with emission limits under certification
conditions but also allowed increased NOx emissions during highway
driving. The U.S. Environmental Protection Agency and ARB consider
those to be defeat devices that result in off-cycle emissions.
1998, Caterpillar, Cummins, Detroit Diesel, Navistar, Mack/Renault
and Volvo signed consent decrees with the EPA, the Department of
Justice and the ARB. The consent decrees stipulate penalties, additional
certification requirements, the Low NOx Rebuild Program, an October
2002 deadline for meeting 2004 model year standards, in-use testing,
and offset and incentive programs.
Low NOx Rebuild Program contained in the consent decrees consists
of engine software upgrades designed to reduce NOx emissions.
consent decrees require low NOx rebuild kits to be installed at
the time of normal engine rebuild, typically around 200,000 to 300,000
miles of service. However, less than 4 percent of the applicable
engines have low NOx rebuild kits installed; nearly 100 percent
order to reduce NOx emissions, ARB is developing a proposal that
would require the low NOx engine software upgrade on all applicable
model year 1993 to 1998 engines.
a list of engines for which low NOx software is available, visit www.arb.ca.gov/msprog/hdsoftware/listofengines/listofengines.pdf. For general information, call ARB's toll-free number,
1-800-END-SMOG (1-800-363-7664) in California, or 1-800-242-4450.