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Vehicle and Engine Certification

Information about Family Naming Conventions for Vehicles and Engines

Guidance Letter

On this page:


Overview

A family is the basic unit that EPA uses to identify a group of vehicles or engines for certification and compliance purposes.

EPA uses many terms for "family", including:
  • Engine family;
  • Test group;
  • Vehicle family;
  • Durability group; and
  • Evaporative and/or permeation and/or refueling family.

A manufacturer should apply for new certificates and pay the appropriate certification fees for each family name that it intends to produce for sale in the United States.

A family name is a 12 character code that identifies all parts of that particular engine.

The typical naming convention is shown below, although some sectors have a slight variation.

The first character is model year code, 2-4 are manufacturer code, 5 is industry sector code, 6-9 is engine displace code or family type descriptor code, and 10-12 is manufacturer's self-designated code.

Note:

For dual or variable displacement families, enter the maximum displacement. If the displacement is given in liters, the decimal point count as a digit. In all cases, the displacement will be read in liters if a decimal point is included and it will be read in cubic inches or cubic centimeters if there is no decimal point.

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Follow these steps to create your family name:

STEP 1: Find the applicable model year code.

From the table below, find the code for Position 1 of your family name.

Code Model Year
1 2001
2 2002
3 2003
4 2004
5 2005
6 2006
7 2007
8 2008
9 2009
A 2010
Code Model Year
B 2011
C 2012
D 2013
E 2014
F 2015
G 2016
H 2017
J 2018
K 2019
L 2020
Code Model Year
M 2021
N 2022
P 2023
R 2024
S 2025
T 2026
V 2027
W 2028
X 2029
Y 2030
Code Model Year
1 2031
2 2032
3 2033
4 2034
5 2035
6 2036
7 2037
8 2038
9 2039

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STEP 2: Determine your manufacturer code.

This code is the 3-character, alpha-numeric code that EPA assigns to each company. Use this code for Positions 2-4 of your family name.

For more information about registering for a manufacturer code, see: 

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Help

For help on using the table:

STEP 3: Find your industry sector.

Click on your industry sector to view specific instructions for determining Positions 5-12 of your family name.

Industry Sector Industry Sector
Code
California-Only Medium-Duty Vehicles A
Large Nonroad Spark-Ignition Engines
(>19 kiloWatts)
B
Highway Motorcycles C
Complete Heavy-Duty Highway Vehicles
(8,500 to 14,000 pounds GVWR; tested on chassis dynamometer)
D
Heavy-Duty Highway Gasoline (otto-cycle/spark ignition) Engines
(>8500 pounds GVWR)
E
Heavy-Duty Evaporative Families F
Locomotives (freshly manufactured) G
Heavy-Duty Highway Diesel (compression ignition) Engines
(>8,500 pounds  GVWR)
H
Light-Duty Vehicles and Light-Duty Trucks/Medium-Duty Passenger Vehicles J
Locomotives (remanufacture system) K
Nonroad Compression-Ignition Engines L
Marine Spark-Ignition Engines M
Marine Compression-Ignition Engines (including IMO) N
Permeation Families P
Light-Duty Evaporative/Refueling Families R
Small Nonroad Spark-Ignition Engines
(<19 kiloWatts)
S
Light-Duty Trucks/Medium-Duty Passenger Vehicles T
Light-Duty Vehicles V
Off-Highway Motorcycles/All-Terrain Vehicles/Utility Vehicles X
Snowmobiles Y
Heavy-Duty Highway Tractors and Vocational Vehicles * 2
Heavy-Duty Highway Trailers 3
Light-Duty Durability Group Various options based on
Combustion Cycle
Note:

* This also includes heavy-duty highway vehicles at or below 14,000 pounds GVWR that are not tested on a chassis-dynamometer for certification under 40 CFR Part 1037 (i.e., certified to the requirements and standards of §1037.105, per §1037.104(f)).

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