Frequently Asked Questions from
                   Owners and Operators of Nonroad
                   Engines, Vehicles,  and  Equipment
                   Certified to EPA Standards
                      The U.S. Environmental Protection Agency (EPA) has adopted
                      emission standards for nearly all types of nonroad engines, vehicles,
                  and equipment. This page describes how EPA emission standards affect
                  individual owners and operators of these products.
                  Why does EPA adopt emission standards for nonroad engines, vehicles, and

                  Nonroad engines contribute significantly to air pollution. The emission standards
                  address emissions of oxides of nitrogen (NOx), hydrocarbons (HC), particulate
                  matter (PM), and carbon monoxide (CO). These emissions help form smog and
                  include toxic compounds such as benzene, so reducing them will benefit our health
                  and environment. In the Clean Air Act, Congress requires us to set emission stan-
                  dards that address these problems.
                  Does my current nonroad engine, vehicle, or equipment need to meet these

                  Manufacturers must ensure that each new engine, vehicle, or equipment meets the
                  latest emission standards. Once manufacturers sell you a certified product, no further
                  effort is required to complete certification. If products were built before EPA emission
                  standards started to apply, they are generally not affected by the standards or other
                  regulatory requirements. See Table 1 for a listing of when EPA emission standards
                  started to apply. We never require owners to retire their old engines, vehicles, or
United States
Environmental Protection
Office of Transportation and Air Quality
                    August 2012

           What requirements apply to owners and operators of certified products?

           One of the most important part of the regulations that applies to you is the tampering prohi-
           bition—you may not disable any emission controls installed on certified engines, vehicles, or
           equipment. This would apply for removing emission control devices, adding or modifying hard-
           ware or software that increases emissions (of any pollutant), reprogramming onboard computers,
           or operating engines without any needed supplies such as Diesel Exhaust Fluid. Manufacturers
           explain in their owner's manual what type of emission controls exist for each model; they may
           also specify some minor maintenance that must be done to keep emission controls working
           properly. For restrictions and recordkeeping requirements that apply for rebuilding engines and
           performing maintenance on certified products, see "How to Maintain or Rebuild Engines Certified
           to EPA Standards," EPA-420-F-12-052 (available at

           Similarly, EPA regulations prohibit defeat devices—you may not make, sell, or install any part
           that bypasses, impairs, defeats, or disables the control of emissions of any regulated pollutant.

           Since manufacturers have the primary responsibility to meet emission standards for their products,
           you generally have no requirements to achieve a certain level of emission control or to re-certify.
           However, you must meet additional requirements in two special circumstances:

               •   You may need to use certified kits or systems when remanufacturing locomotive engines
                  or marine diesel engines,
               •   In the case  of Marine SI engines (40 CFR part 1045), Recreational vehicles (40 CFR
                  part 1051),  and Small SI engines (40 CFR part 1054), you must re-certify if you up-
                  grade your engine to operate on a different fuel. For fuel conversions with other types of
                  nonroad engines, vehicles,  or equipment, you may need to do testing to show that the
                  conversion  is not considered tampering, but you do not need to re-certify.
            What kind of emission controls does EPA require?

            We don't tell manufacturers what emission controls to use to comply with the regulations, but
            we rely on testing information from engines equipped with specific technologies to establish the
            emission standards. Manufacturers may use these anticipated technologies, or they may find
            better ways to meet emission standards.

            Manufacturers of diesel engines have typically met the standards with more careful control of
            intake air and fuel injection, with some exhaust gas recirculation. Long-term standards for many
            of these engines will generally involve additional use of aftertreatment devices such as diesel
            particulate filters (DPF) and selective catalytic reduction (SCR),
  -~        Most Large SI engines and many Marine SI engines use automotive -type technologies, including
           closed-loop fuel injection and three-way catalytic converters. For other engines, manufacturers
           will optimize air-fuel mixtures and make other internal engine changes. We expect continued
           use of two-stroke engines in the following cases: (1) outboard and personal watercraft marine
           engines may use direct-injection two-stroke engine technology, which avoids the most prob-
           lematic aspects of two-stroke combustion; (2) to maintain lightweight performance, Handheld

           Small SI engines will typically continue to use two-stroke engines, though these engines will
           generally have catalysts to reduce the amount of unburned fuel from escaping through the
           exhaust as hydrocarbon emissions; and (3) some two-stroke snowmobile engines will likely con-
           tinue to be available, depending on ongoing efforts to improve the performance characteristics
           of four'Stroke snowmobile engines.

           For gasoline-fueled products, we have also adopted requirements to control permeation emis-
           sions from fuel systems. We expect these requirements to lead to the use of improved materials
           to prevent fuel from escaping through fuel tanks and hoses into the atmosphere. This should
           noticeably reduce the smell of gasoline around these vehicles and equipment.
       How will these controls affect performance and safety?

       As part of the rulemaking process, we evaluate potential safety issues related to new standards
       to make sure not to adopt emission standards that would cause manufacturers to use emission
       controls that add new risks to operating vehicles or equipment. As always, it is important to
       take proper precautions when using engine-powered vehicles or equipment.

       Meeting emission standards adds to the engine designer's challenge. This might lead to some
       trade-offs with respect to power or efficiency; however, there are many examples of design engi-
       neers coming up with ways to add emission controls in a way that significantly improves engine
       power and efficiency while reducing emissions. Over time, engineers will work to improve
       designs to reduce or eliminate any remaining trade-offs,

       Do EPA regulations  affect where I can use my nonroad vehicle or equipment?

       No. These regulations do not include any specific restrictions about where you can use your
       nonroad vehicle or equipment. They address only the permissible emission rates from new,
       certified products.

       State and local governments have limited authority to set emission standards for new products;
       however, they may adopt regulations that restrict the use and operation of most products that
       are no  longer new. EPA generally has no involvement with such restrictions.
       Do EPA regulations apply in California?

       California has adopted its own emission standards for certain types of new nonroad engines,
       vehicles, or equipment. In those cases, manufacturers must certify their products with the
       California Air Resources Board; these products are also certified with EPA even though no
       additional requirements apply,

       EPA's prohibitions against tampering and defeat devices apply to certified products throughout
J      the United States, including products that are certified to meet emission standards that apply
       uniquely in California,

             For More Information
             You can access documents related to emission standards for nonroad engines, vehicles, and
             equipment on EPA's Office of Transportation and Air Quality (OTAQ) web site at:


             You can also contact the OTAQ library for document information at:

                      U.S. Environmental Protection Agency
                      Office of Transportation and Air Quality Library
                      2000 Traverwood Drive
                      Ann Arbor, Michigan 48105
                      (734)  214-4311& 214-4434
                                                  Table 1
             Schedule for Application of New Emission Standards for Certifying Engines and Vehicles
Engine category
A. Heavy-duty highway engines
B. Locomotives or locomotive
C. Marine compression-ignition
engines at or above 37 kW
D. Other nonroad compression-
ignition engines.
E. Marine spark-ignition engines.
F. Recreational spark-ignition
engines and vehicles
G. Other nonroad spark-ignition
engines at or below 1 9 kW
H. Other nonroad spark-ignition
engines above 19 kW
Engine subcategory
Commercial: displacement < 0.9 L/cyl
Commercial: 0. 9 £ displacement < 2.5 L/cyl
Commercial: displacement > 2.5 L/cyl
Recreational: displacement < 0.9 L/cyl
Recreational: 0.9 < displacement < 2.5 L/cyl
Recreational: 2.5 < displacement < 5.0 L/cyl
Marine compression-ignition engines: Power < 19 kW
Marine compression-ignition engines: 19 kW < Power < 37
Nonroad engines: Power < 19 kW
Nonroad engines: 19 kW< Power < 37
Nonroad engines: 37 kW< Power < 75
Nonroad engines: 75 kW< Power < 130
Nonroad engines: 130 kW < Power < 560
Nonroad engines: Power > 560 kW
Personal watercraft
Manufacturing date
after which emission
standards start to apply
Model year 1970
January 1, 1973
Model year 2005
Model year 2004
Model year 2007
Model year 2007
Model year 2006
Model year 2009
January 1, 2000
January 1, 1999
January 1, 2000
January 1, 1999
January 1, 1998
January 1, 1997
January 1, 1996
January 1, 2000
Model year 1998
Model year 1999
Model Year 2010
Model year 2006
Model year 1997
Model year 2004