Commonly Used Terms

ASM TEST: Acceleration Simulation Mode Test 

A loaded-mode test that measures tailpipe emissions when a vehicle is running under marginal load and at a steady rate or revolutions per minute (rpm).  

BASIC AREA 

The EPA designation for a “moderate” ozone non-attainment area, which is subject to less stringent emissions controls than an Enhanced area. 

CENTRALIZED SYSTEM 

A state-appointed contractor or state agency purchases and constructs test-only stations, hires inspection personnel and performs all other functions of vehicle emissions testing. 

CNG 

Refers to a Compressed Natural Gas powered vehicle 

CUTPOINTS 

Fail point listed for each test types. Any reading higher than a cutpoint is a fail. 

DECENTRALIZED SYSTEM

Testing is conducted by independently owned businesses not exclusively dedicated to vehicle testing (e.g., repair shops). 

DYNAMOMETER 

A treadmill-like device that simulates vehicle inertia and road load to derive results under conditions similar to everyday driving. 

EGR

Exhaust gas recirculation valve 

EPA DESIGNATION 

The classification given to a state area based on its level of air pollution. This classification determines the strictness of the area’s vehicle testing program (e. g., Basic, Enhanced). 

ENHANCED AREA

The EPA designation for a “severe” and /or “extreme” ozone non-attainment area (over 12.7 ppm) with an urbanized population greater than 200,000.  

GASCAP TEST

A Gas Cap Test is a functional check that tests whether harmful evaporative emissions 

(fumes) are escaping from a vehicle’s gas tank into the atmosphere. The gas cap is removed and inserted into a device that then applies pressure to the gas cap. The testing unit will verify that the gas cap holds pressure for a period of approximately 45 seconds and a determination will be made as to whether or not fumes are escaping. 

HDDV 

Heavy Duty Diesel Vehicle 

HDGT 

Heavy Duty Gas Truck 

HDGV 

Heavy Duty Gasoline Vehicle 

HYBRID PROGRAM 

Any emissions inspection program utilizing both centralized test-only sites and decentralized test-and-repair facilities. It is also used to describe any program that is not strictly a centralized or decentralized system.  

I/M 240 TEST 

A transient high-tech inertia weight dynamometer I/M test for HC, CO and NOx tailpipe emissions, which lasts for 240 seconds and utilizes lab quality bench analyzers. 

LDDV 

Light Duty Diesel Vehicle 

LDGV 

Light Duty Gasoline Vehicle 

LDGT 

Light Duty Gasoline Truck 

LOADED-MODE TEST 

A reference to a test that uses a dynamometer. 

LPG 

Refers to a Liquid Propane Gas powered vehicle 

MC 

Motorcycle 

OBD: ON-BOARD DIAGNOSTICS 

An on-board system comprised of a computer with diagnostic software and sensors. The OBD system monitors the performance of the ignition, fuel metering and emissions systems, including the sensors and the computer itself, while the vehicle is being driven to insure they are working “as designed.” When the OBD system detects a problem, a diagnostic trouble code is stored in the vehicle’s computer. The OBD I/M Check can be performed on most 1996 and newer model-year gasoline powered passenger vehicles, vans and light-duty trucks weighing 8,500 pounds and less, since these vehicles were required by the EPA to be manufactured with OBD systems. 

PCV 

Positive Crankcase Ventilation valve. 

PRESSURE TEST 

A test that checks for leaks in the evaporative system that would allow fuel vapors to escape into the atmosphere. 

RG 240 TEST 

A “light” version of I/M 240 employing less costly equipment designed for use in repair shop bays. 

SIP 

State Implementation Plan (SIP) 

TAILPIPE TEST 

A Tailpipe Test uses a tailpipe probe to collect a sample of the exhaust and an emissions analyzer to measure pollutants while the engine is idling. The Tailpipe Test can be performed on many gasoline-powered passenger vehicles, vans and light-duty trucks. Inspection requirements are based on each vehicle’s model year, with an allowance for normal wear.