UPDATED INFORMATIVE DIGEST

AMENDMENTS TO CALIFORNIA’S SMALL OFF-ROAD ENGINE AND TIER 4 

OFF-ROAD COMPRESSION-IGNITION ENGINE REGULATIONS AND TEST 

PROCEDURES; AND AMENDMENTS TO THE EXHAUST EMISSION 

CERTIFICATION TEST FUEL FOR OFF-ROAD SPARK-IGNITION ENGINES,

EQUIPMENT, AND VEHICLES

Sections Affected:

Small Off-Road Engines (SORE) sections 2403 and 2407; and to the following 

document as incorporated by reference therein: “California Exhaust Emission Standards 

and Test Procedures for 2005 and Later Small Off-Road Engines,” as adopted July 26, 

2004, and as last amended February 24, 2010; and the following documents 

incorporated by reference therein: “California Exhaust Emission Standards and Test 

Procedures for New 2013 and Later Small Off-Road Engines; Engine-Testing 

Procedures (Part 1054)”; and “California Exhaust Emission Standards and Test 

Procedures for New 2013 and Later Small Off-Road Engines; Engine-Testing 

Procedures (Part 1065)”; and

Off-Road Compression-Ignition (ORCI) Engines sections 2421, 2423, 2424, 2425, 

2425.1, 2426, and 2427; and to the following document as incorporated by reference 

therein: “California Exhaust Emission Standards and Test Procedures for New 2008 and 

Later Tier 4 Off-Road Compression-Ignition Engines, Part I-C,” adopted October 20, 

2005; and to the following documents incorporated by reference therein: “California 

Exhaust Emission Standards and Test Procedures for New 2011 and Later Tier 4 

Off-Road Compression-Ignition Engines, Part I-D,” adopted October 20, 2005; and 

“California Exhaust Emission Standards and Test Procedures for New 2011 and Later 

Tier 4 Off-Road Compression-Ignition Engines, Part I-F,” adopted October 20, 2005; 

and adoption of the following document incorporated by reference therein: “California 

Exhaust Emission Standards and Test Procedures for New 2011 and Later Tier 4 

Off-Road Compression-Ignition Engines, Part I-E”; and 

Off-Road Large Spark-Ignition (LSI) Engines sections 2433, 2783, and 2784; and to the 

following documents incorporated by reference therein: “California Exhaust and 

Evaporative Emission Standards and Test Procedures For New 2010 and Later 

Off-Road Large Spark-Ignition Engines (2010 and Later Test Procedure 1048),” as 

adopted March 2, 2007, and as last amended November 21, 2008; and “California 

Exhaust and Evaporative Emission Standards and Test Procedures For New 2007 and 

Later Off-Road Large Spark-Ignition Engines (Test Procedures 1065 and 1068),” as 

adopted March 2, 2007; and
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Off-Highway Recreational Vehicles (OHRV) section 2412; and to the following 

document incorporated by reference therein: “California Exhaust Emission Standards 

and Test Procedures for 1997 and Later Off-Highway Recreational Vehicles and 

Engines," as adopted May 26, 1995, and as last amended June 1, 2007; and

Spark-Ignition Marine Engines (SIME) section 2447; and to the following document 

incorporated by reference therein: “California Exhaust Emission Standards and Test 

Procedures for 2001 Model Year and Later Spark-Ignition Marine Engines,” as adopted 

October 21, 1999, and as last amended June 5, 2009.

Background:

Health and Safety Code (HSC) sections 39600 (General Powers), 39601 (Standards, 

Definitions, Rules and Measures), and 39602.5 (Adoption of Rules and Regulations) 

direct the Air Resource Board (ARB or Board) to adopt rules and measures necessary 

to execute the Board’s powers and duties imposed by State law and to attain federal

national ambient air quality standards in all areas by applicable attainment dates. HSC

sections 43013 and 43018(a) provide broad authority to achieve the maximum feasible 

and cost-effective emission reductions from all mobile source categories, including both 

new and in-use on-road and off-road engines used in motor vehicles.

California's Air Toxics Program, established under California law by Assembly Bill (AB)

1807 (stats. 1983, ch. 1047, the Tanner Act) and set forth in HSC sections 39650 

through 39675, also mandates that ARB identify and control air toxic emissions in 

California. Following the identification of a substance as a toxic air contaminant, HSC 

section 39665 requires ARB, with the participation of the local air pollution control and 

air quality management districts (Districts), and in consultation with affected sources 

and interested parties, to prepare a report on the need and appropriate degree of 

regulation for that substance. Based upon the findings of the report, ARB is vested with 

authority under sections 39666 and 39667 to adopt and enforce airborne toxic control 

measures that will respectively achieve emission reductions using best available control 

technology for nonvehicular and vehicular sources.

Small Off-Road Engines

In 1990, ARB approved the initial exhaust emission control regulations for new SORE. 

These regulations included exhaust emission standards, emission test procedures, and 

provisions for warranty and production compliance programs, which are contained in 

title 13, California Code of Regulations (CCR), sections 2400-2409, along with the 

applicable test procedures which are incorporated by reference. Later, the U.S.

Environmental Protection Agency (U.S. EPA) adopted similar but less stringent 

regulations and test procedures for small “nonroad” spark-ignition engines, which were 

introduced in title 40, Code of Federal Regulations (CFR), Part 90 (40 CFR Part 90). 
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In 2003, ARB adopted more stringent SORE exhaust emission standards, and also 

aligned, with some modifications (ARB 2003), with U.S. EPA’s small nonroad engine 

test procedures in 40 CFR Part 90. 

In November 2008, ARB adopted modifications to the emission credit program for 

SORE, including adding a zero-emission equipment credit program and an option to 

certify using a 10-percent ethanol-blend (E10) of gasoline, as well as other minor 

modifications to the regulations (ARB 2008). 

Off-Road Compression-Ignition Engines

In 1990, the Board adopted the very first emission standards for new ORCI engines for 

engines less than 19 kilowatts (kW) as part of the California requirements for 1995 and 

later small off-road engines. In 1992, the Board approved standards for ORCI engines 

130 kW and greater, which became known as the tier 1 standards. These standards 

were implemented beginning in 1996 and resulted in approximately a 50-percent drop in 

oxides of nitrogen (NOx) emissions compared to previously uncontrolled engines. 

Also in 1992, the Board adopted a second tier of more stringent emission standards, 

known as tier 2. These original tier 2 standards were to apply to engines with rated 

power 130 ≤ kW ≤ 560 beginning in 2000. However, in response to U.S. EPA’s 1998 

adoption of even more stringent tier 2 emission standards to start in 2001, ARB fully 

aligned California’s standards and implementation schedules with U.S. EPA’s 

requirements in 2000 (ARB 1999). Tier 2 requirements were phased-in from 2001 

through 2010, and encompassed the entire power spectrum of engine applications 

including those above 560 kW and those under 19 kW. 

ARB also adopted U.S. EPA’s tier 3 standards, which were phased-in from 2006 

through 2011 and were applicable to engines with rated power 37 ≤ kW ≤ 560. The new 

standards have reduced non-methane hydrocarbons plus NOx (NMHC + NOx)

emissions by an additional 40 percent compared to the previous tier 2 standards. 

However, tier 3 particulate matter (PM) standards are the same as tier 2 PM standards. 

In 2004, ARB adopted interim and final tier 4 emission standards. Tier 4 interim 

standards began in 2008 for some engines and required maximum control of PM and 

NMHC emissions, but only moderate control of NOx emissions, primarily to allow for the 

maturation of advanced aftertreatment NOx control technologies. Tier 4 final standards

typically begin 3 or 4 years after the start of the interim standards for each power 

category and generally require engines to meet significantly more stringent advanced 

aftertreatment-based PM and NOx standards.

U.S. Environmental Protection Agency Nonroad Regulations and Test Procedures

California’s Off-Road Exhaust Emission Certification Test Fuel
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In 2007, ARB amended the Phase 3 reformulated gasoline (CaRFG3) regulations by 

essentially increasing the amount of fuel oxygenates (i.e., ethanol) in California’s 

commercially available gasoline from 5.7 percent (i.e., E6) to 10 percent (i.e., E10) by 

December 31, 2009. Staff recognized that there was limited ethanol-based emission 

test data available from off-road, spark-ignition engines during this rulemaking.

On January, 27, 2012, ARB adopted an E10 gasoline certification test fuel specification 

for on-road motor vehicles. Accordingly, the Board adopted the same fuel for use in 

California’s off-road spark-ignition engine categories to re-establish the consistency that 

had existed originally between the off-road categories’ certification and commercially 

available fuels.

Description of Regulatory Action:

On December 16, 2011, the Board conducted a public hearing to consider staff’s 

proposal as described in the Staff Report. At the hearing’s conclusion, the Board voted 

to amend California’s off-road exhaust emission regulations for new SORE and tier 4 

ORCI engines. The amendments, overall, provide better harmonization with federal 

certification and exhaust emission testing requirements for SORE and tier 4 ORCI 

engine regulations and associated test procedures. The amendments create a more 

efficient certification process for engine and equipment manufacturers by removing the 

burden to perform duplicative testing for California and federal certification. The 

amendments to the tier 4 ORCI engine regulations also provide for more descriptive 

labeling requirements, which will facilitate the implementation and enforcement of ARB’s 

various in use programs in California. 

Furthermore, the Board approved modifications to the exhaust-emission certification 

test fuel requirements used in the gasoline-fueled SORE, LSI engines, OHRV, and 

SIME off-road categories. These amended requirements require a ten-percent ethanolblend of gasoline, which would be the same as the on-road motor vehicle test fuel 

requirement that was approved by the Board on January 27, 2012, or other fuel blends 

approved by ARB as appropriate for use in off-road categories.

Staff also proposed various editorial corrections and several modifications to the 

proposed regulatory action. Written and oral comments were received at the hearing 

concerning staff’s proposal. A Notice of Public Availability of Modified Text containing 

the Board directed amendments to the regulation was released for a 15-day comment 

period on March 22, 2012, the results of which have been incorporated as attachments 

to the Final Statement of Reasons for this rulemaking. 

A full description of the amendments can be found in the “Staff Report: Initial Statement 

of Reasons,” with the other regulatory documents for this rulemaking, at 

http://www.arb.ca.gov/regact/2011/soreci2011/soreci2011.htm.

The Board also adopted other non-substantive modifications to the affected regulations

and test procedures to clarify or simplify existing language.
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COMPARABLE FEDERAL REGULATIONS

In 2001, U.S. EPA adopted title 40, CFR, Part 1065, as a “united” test procedure for 

both “nonroad” engines and equipment and on-highway heavy-duty CI engines. The 

test procedures in Part 1065 essentially replaced those previously used in Part 90 for 

nonroad spark-ignition engines and those in Part 89 for nonroad CI engines. Part 1065 

is currently the technical part of U.S. EPA’s regulations that promulgates emissions 

measurement methodologies, criteria for selecting analytical instrumentation, calibration 

procedures, and specifications for virtually all engine categories. Since its initial 

adoption, Part 1065 has been amended repeatedly to both improve and expand its 

applicability for the nonroad engine categories. In addition, U.S. EPA adopted specific 

“standard-setting” parts for each engine/equipment and vehicle category. Besides the 

actual emission standards, these standard-setting parts contain other provisions, such 

as certification protocols, production-line testing requirements, credit-generation 

allowances, etc. Also adopted was Part 1068, which is the general compliance, special 

provisions, and defect reporting part of U.S. EPA’s regulations.

Since 2005, U.S. EPA has adopted several amendments to its nonroad CI engine 

regulations contained in Parts 1039, 1065, and 1068. Federal nonroad CI engines 

certified to the more stringent “tier 4” emission standards must be tested using Part 

1065. Use of Part 1065 is optional for less stringent “tier 3” and earlier model engines. 

Part 1039 is the standard-setting part of U.S. EPA’s regulations for nonroad CI engines, 

and also contains provisions regarding certification procedures, labeling, credit 

generation, emissions averaging, equipment flexibility options, and hardship relief.

In 2008, U.S. EPA adopted exhaust and evaporative emission standards for small 

nonroad engines, which coincided with some of ARB’s SORE emission standards that 

were adopted in 2003. At the same time, U.S. EPA divided up the small nonroad 

engine requirements that were contained in the then-current Part 90, and distributed 

these requirements into other parts. The applicable small nonroad engine test 

procedures are now contained in Part 1065; the standard-setting provisions for small 

nonroad engines are now contained in Part 1054; and, the small nonroad engine 

general compliance requirements are now contained in Part 1068. Also at that time, 

U.S. EPA set the requirement that nonroad small engines had to be tested using the 

Part 1065 test procedures starting with the 2013 model year, although carry-over of 

engines already certified using the older Part 90 test procedures would still be allowed.

BENEFITS OF THE PROPOSAL

These modifications and additions to the regulations and test procedures preserve the 

stringency of the existing emission standards and effectiveness of the associated test 

procedures while creating greater harmonization with similar requirements already 

promulgated by U.S. EPA. The harmonization of requirements where possible 

facilitates certification and allows manufacturers to better utilize resources. The 

adopted amendments do not require manufacturers to generate additional emission 

benefits, nor do they permit a decrease overall from existing benefits. Based on ARB’s 
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review of the proposed regulatory action, staff has concluded that the amendments to 

SORE, tier 4 off-road CI engine, and off-road spark-ignition engine regulations and test 

procedures (including the certification test fuel changes), would not have a significant 

adverse effect on the environment. No discussion of alternatives or mitigation 

measures is necessary because there are no significant adverse environmental impacts 

identified.