California Air Resources Board

The certification requirements for heavy-duty engines installed in vehicles with a Gross Vehicle Weight Rating (GVWR) greater than 14,000 lbs. are contained in Title 13, California Code of Regulations, Section 1956.8 (13 CCR 1956.8) .  Also, manufacturers of engines intended for medium-duty vehicles (10,000 to 14,000 lbs.) may elect to certify using the heavy-duty engine requirements in lieu of the chassis certification procedures.  The provisions of 13 CCR incorporate the California Test Procedures which contain altered or replaced sections of Parts 86, 1036, and 1065, Title 40 Code of Federal Regulations (40 CFR) relevant to heavy-duty engines.  

Heavy-Duty Low-NOx certified engines are listed on the Optional Reduced NOx Standards for Heavy-duty Vehicles webpage.

Engine Families 

Engines with similar emissions characteristics are grouped into engine families and certified together.  Similarity criteria are described in paragraphs (i) through (x) of 40 CFR 86.096-24(a)(2).  Emission standards for criteria and greenhouse gas pollutants for families of medium-duty and heavy-duty Diesel and Otto Cycle engines are contained in 13 CCR 1956.8 and incorporated California test procedures. Each engine family must be assigned a unique family name by the manufacturer, in accordance with the established EPA family naming conventions.

For more information, please review the Heavy-Duty Engine and Vehicle Omnibus Regulation and Associated Amendments. 

Engine Carbon Dioxide Emissions Reporting Requirments

All on-road engine manufacturers are required to report Carbon Dioxide emissions measured during the certification emissions tests. This is a reporting requirement applicable to all 2008 and subsequent model year engines. Certifying engine manufacturers must include the measured carbon dioxide emissions in their certification applications. See Mail-Out MSO #2007-03 for more information. 

Engine Idling Requirements

Heavy-Duty engines are subjected to Heavy-Duty Diesel Engine Idling Requirements outlined in 13 CCR 1956.8 (a)(6), and Otto-Cycle requirements in 13 CCR 1956.8(c)(1)(B)(footnote "G"). 

For more information about engine idling requirements, please see MAC 2007-03: Protocol for the Engine Shutdown System on New California Certified Heavy-Duty Diesel Engines for 2008 and Subsequent Model Years.

The following vehicles are exempted from the engine idling requirements:

• Heavy-duty diesel engines to be used in buses as defined in California Vehicle Code sections 233, 612 and 642
• School buses as defined in California Vehicle Code section 545
• Recreational vehicles as defined in Health and Safety Code 18010
• Medium duty vehicles as defined in section 1900(b)(13) of title 13, California Code of Regulations
• Military tactical vehicles as defined in section 1905 of title 13, California Code of Regulations
• Authorized emergency vehicles as defined in California Vehicle Code section 165
• Armored cars, as defined in California Vehicle Code sections 115
• Workover rigs, as defined in section 2449 of title 13, California Code of Regulations

For all Otto-cycle heavy-duty engines utilizing aftertreatment technology, and not certified to the on-board diagnostics requirements of section 1968, et seq, as applicable, the CO emissions shall not exceed 0.50 percent of exhaust gas flow at curb idle. However, in practice, all new Heavy-Duty Otto-Cycle engines are certified to the OBD requirements, therefore the engine idling requirements do not apply to new Heavy-Duty Otto-Cycle engines.  

Innovative Technologies

The Innovative Technology Regulation (ITR) provides certification flexibility for heavy-duty engines and engines installed in hybrid vehicles. Heavy-duty engines that are applicable to ITR include low NOx engines, high-efficiency engines, and engines intended for specific types of heavy-duty hybrids.

ITR also defines protocols for certification of truck and bus hybrid conversion systems (also commonly referred to as hybrid aftermarket systems or conversion kits) to further encourage deployment of robust hybrid technology in California's truck and bus fleet.

Alternative Fuel Retrofit Systems

The Alternative Fuel Retrofit Regulation contains certification and installation procedures for alternative fuel retrofit systems designed for used 2004 and subsequent model year on-road heavy-duty vehicles. Alternative fuel retrofit systems are certified through the Aftermarket, Performance, and Add on Parts program.

CARB conducted a public workshop on August 14, 2012 to describe certification of alternative fuel retrofit systems for 2004 and subsequent model year in-use vehicles and engines in such vehicles. The workshop presentation includes pathways, requirements, and other certification information.  The workshop notice was issued on July 20, 2012.