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Fact Sheet for Alternative Fuel System Conversions

6 NYCRR Part 218, Emissions Standards for Motor Vehicles & Motor Vehicle Engines

New York State adopted California's new motor vehicle emissions program, also known as the low emission vehicle program (LEV), in 1990 with implementation beginning with applicable model year 1993 vehicles. New York has the authority to adopt the LEV standards pursuant to Section 177 of the federal Clean Air Act and the New York State Environmental Conservation Law.

The Department of Environmental Conservation (Department) implemented New York's LEV regulations under 6 NYCRR Part 218. (link leaves DEC's website) These regulations apply to new on-road motor vehicles delivered for sale in New York State. New vehicles subject to the regulation must be certified to either California emission standards or "50 State" vehicle emission standards when offered for sale within New York State. Emissions certification information can be found on each vehicle's Vehicle Emission Control Information (VECI) label.

Part 218 also includes provisions for aftermarket, performance, and add-on parts. These provisions are incorporated in Subpart 218-7: Aftermarket Parts, (link leaves DEC's website) and apply to new and used on-road motor vehicles. Subpart 218-7 prohibits the sale, installation, and advertisement of non-compliant emissions control systems, devices, or parts, and also prohibits the modification or alteration of the original design or performance of such parts. Parts or modifications, including alternative fuel system conversions, are permitted provided they have been certified for use by the California Air Resources Board (CARB) or the U.S. Environmental Protection Agency (EPA) and have been proven not to increase vehicle emissions. Alternative fuel system conversions include, but are not limited to: bi-fuel, dual fuel, and dedicated compressed natural gas (CNG); full battery electric; plug-in hybrid electric; hybrid electric; and bio-diesel.

In New York State, CARB certified alternative fuel system conversions are required for vehicles that were originally certified to CARB emission standards. EPA certified conversions are required for vehicles that were originally certified to federal emission standards. EPA recently revised its alternative fuel system conversion requirements and created new procedures for new vehicles (less than 2 years old), intermediate age (2 years up to vehicle's full useful life, usually 10 years), and outside of useful life (typically more than 10 years old). CARB has not adopted similar procedures. The fuel system conversion is generally certified by CARB or EPA for use on a particular make, model(s) or engine family, and model year(s).

Replacing a vehicle's engine with another engine, also known as "engine switching," is allowed under certain conditions. Generally, engine switching is allowed if the replacement engine is a certified configuration of the same model and model year or newer. Switching to an older engine configuration, switching to a different fuel type, or using an engine from a different make/model may constitute tampering with an emissions control device. A link to EPA's engine switching fact sheet is provided at the end of this fact sheet.

Use of an uncertified fuel system conversion, use of a certified system on a vehicle make/model/model year not included in the certification, or use of a CARB certified system on an EPA certified vehicle, or vice versa, may constitute tampering with an emissions control device and could result in enforcement action by the Department. Per New York State Environmental Conservation Law (ECL) §71-2103, violations of Part 218 are subject to fines of at least $500 for a first violation and up to $26,000 for each subsequent violation. The federal tampering prohibition is contained in §203(a)(3) of the Clean Air Act 42 USC 7522(a)(3), and establishes maximum penalties per violation of $25,000 for manufacturers and $2,500 for individuals.

Examples of Potentially Illegal Conversions

Uncertified dedicated, bi-fuel, or dual fuel CNG or propane systems

  • Bio-diesel conversions, also known as vegetable oil or grease car conversions
  • On-board hydrogen generators
  • Converting hybrid electric vehicle to plug-in hybrid electric
  • Engine switching, typically replacing gasoline engine with diesel or bio-diesel engine
  • Removing and/or disabling certified emissions control components


Links to the following can be found under "Offsite Links" in the right hand column.

  • CARB Aftermarket, Performance, and Add-On Parts
  • EPA Alternative Fuel Conversion Requirements and Lists of Compliant Systems
  • EPA Engine Switching Fact Sheet - can be found on EPA's Air Enforcement Policy, Guidance and Publications web page under mobile sources of air pollution, Vehicles/Engines.

Any questions related to compliance with Part 218 should be directed to this office.