Mobile Sources

This photograph taken by NASA shows a cloud of smog hugging the circumference of earth.  Courtesy of NASA.

EES | Cases by Practice Area

Clean Air Act Mobile Source Cases


The emission of pollution - including carbon monoxide, oxides of nitrogen, and hydrocarbons - from cars, trucks and engines that go into other types of equipment (e.g., lawnmowers, generators and construction equipment) is regulated under Title II of the Clean Air Act, often referred to as the “mobile source” title because the sources of air pollution covered by this title are mobile. Air pollution from mobile sources accounts for more than half of the air pollution in the United States today.

The Environmental Protection Agency (EPA) sets emission limits for different classes of motor vehicles and engines. In order for a manufacturer to lawfully import or introduce into commerce in the United States vehicles or engines, the vehicles or engines must be covered by a Certificate of Conformity (like a license) issued for each model year demonstrating that the vehicle or engine will meet the applicable emission limits throughout its useful life. This is done by pre-certification emissions testing of one or more representative vehicles or engines.

Enforcement Actions

The Environmental Enforcement Section, on behalf of EPA has brought numerous actions against manufacturers that fail to comply with Title II requirements.

Actions Against Entities that Import and Sell Uncertified Vehicles and Engines and/or Fail to Properly Label the Engines or Provide Required Warranties

The Clean Air Act and the regulations adopted by EPA to implement Title II make it unlawful to import or introduce into commerce vehicles or engines that are not covered by a Certificate of Conformity. This includes situations:

  • where a manufacturer does not apply for a Certificate at all;
  • and situations where the vehicle or engine which a manufacturer claims is covered by a Certificate of Conformity does not in fact conform in all material respects to the design specifications in the certificate.

Absent a valid certificate there is no way for EPA to be assured that the particular vehicle or engine in fact will meet the emission limits.

Manufacturers also must properly label their engines, offer specified emission system warranties, and timely report emission-related defects to EPA so that EPA can determine if a recall is needed.

Actions Against Manufacturers that Fail to Timely Report Defects

The Clean Air Act and the regulations adopted by EPA to implement Title II require that manufacturers provide EPA with notice of emissions related defects within specified time periods.  This enables EPA to determine what actions, if any, are necessary to address the defect.

Actions Involving Defeat Devices

Under the Clean Air Act it is generally unlawful for a manufacturer to equip its vehicles or engines with a “defeat device” which reduces the effectiveness of the emission control system. A defeat device often results in the vehicle or engine emitting more pollution than indicated in the pre-certification testing.

Defeat device cases can involve computer code that controls how the engine operates under different conditions.

The largest action brought by the Department of Justice on behalf of EPA relating to this defeat device prohibition was the 1998 action against seven manufacturers of heavy duty diesel engines, representing 95 percent of the U.S. heavy duty diesel engine market. However, other significant defeat device cases have been brought. A different kind of defeat device can involve aftermarket components, which are often sold on-line.  These devices can change engine operations in different ways that can effect emissions, such as  by  tricking the car’s onboard diagnostic system into sensing that the car’s emission system was properly functioning (and therefore not trigger the dashboard check engine light) even if the car’s catalytic converter had been removed.

In the News

March 24, 2015
MTU America Inc. Agrees to $1.2 Million Penalty and Auditing Program to Resolve Clean Air Act Violations
MTU America Inc. (MTU), a subsidiary of Rolls-Royce Power Systems AG, will implement an auditing program to ensure proper emissions testing and compliance with federal emission standards for its heavy-duty diesel non-road engines as part of a settlement to resolve alleged Clean Air Act violations, the Department of Justice and the U.S. Environmental Protection Agency (EPA) announced today. The complaint filed with the settlement alleges that MTU violated the Clean Air Act by selling 895 non-road, heavy-duty diesel engines, which are used in mining, marine and power generation vehicles and equipment, without valid certificates of conformity.  EPA voided the certificates of conformity purporting to cover the engines based on improper emissions testing by MTU employees.  Under the settlement, MTU will pay a $1.2 million penalty and perform annual audits of its engine emission testing and certification activities for three years. 

November 3, 2014
United States Reaches Settlement with Hyundai and Kia in a Historic Greenhouse Gas Enforcement Case
The Department of Justice and the U.S. Environmental Protection Agency (EPA) today announced a historic settlement with the automakers Hyundai and Kia that will resolve alleged Clean Air Act violations based on their sale of close to 1.2 million vehicles that will emit approximately 4.75 million metric tons of greenhouse gases in excess of what the automakers certified to EPA. The automakers will pay a $100 million civil penalty, the largest in Clean Air Act history, to resolve violations concerning the testing and certification of vehicles sold in America and spend approximately $50 million on measures to prevent any future violations.  Hyundai and Kia will also forfeit 4.75 million greenhouse gas emission credits that the companies previously claimed, which are estimated to be worth over $200 million. 

January 17, 2013
Automotive Electronics Manufacturer Fined $500,000 for Selling Illegal Devices Resulting in Tons of Excess Particulate Matter Emissions
In a settlement with the United States on behalf of the U.S. Environmental Protection Agency, automotive electronics manufacturer Edge Products LLC (Edge) has agreed to pay a $500,000 civil penalty for manufacturing and selling electronic devices that allowed owners of model year 2007 and later diesel pickup trucks to remove emission controls from their vehicles.

November 13, 2012
Vehicle and Engine Importers to Pay Civil Penalty to Resolve Clean Air Act Violations
The Department of Justice and the U.S. Environmental Protection Agency (EPA) today announced a settlement with two former importers of highway motorcycles, recreational vehicles and small spark ignition engines.   The defendants, Yuan Cheng International Group Inc. (YCIG) and NST Inc. (NST), located in Montclair, Calif., allegedly imported and sold vehicles and engines from China without proper certifications in violation of Clean Air Act requirements.

March 28, 2012
Shipbuilder and Ship Engine Manufacturer Agree to Pay Civil Penalty and Perform Environmental Project to Resolve Clean Air Act Violations
Coltec Industries Inc. and National Steel and Shipbuilding Company (NASSCO) have agreed to pay a civil penalty of $280,000 and spend approximately $500,000 on an environmental project to resolve alleged violations of the Clean Air Act (CAA) and EPA’s marine diesel engine air rules by manufacturing and selling marine diesel engines that were not covered by an EPA-issued certificate of conformity and by selling such engines with missing or improper emissions compliance labels required by EPA’s regulations.

July 28, 2011
Caterpillar Inc. to Pay $2.55 Million Penalty to Resolve Clean Air Act Violations
Caterpillar Inc. has agreed to pay a $2.55 million civil penalty to settle alleged Clean Air Act violations for shipping more than 590,000 highway and non-road engines without the correct emissions controls.

February 28, 2011
Mississippi Companies to Pay $2 Million for Selling Thousands of Engines from China That Failed to Meet Clean Air Act Standards
Mississippi-based PowerTrain Inc., Wood Sales Inc., and Tool Mart Inc., (collectively known as “PowerTrain”) will jointly pay a civil penalty of $2 million to resolve claims that the company imported and sold almost 80,000 non-road engines and equipment that were not covered by emissions-related certificates of conformity, and in most cases could not be certified because they exceeded emissions standards under the Clean Air Act.

May 10, 2010
Pep Boys Agrees to Pay $5 Million to Resolve Clean Air Act Violations Claims
The Pep Boys – Manny, Moe & Jack - have agreed to pay $5 million in civil penalties and take corrective measures to settle claims that it violated the Clean Air Act by importing and selling motorcycles, recreational vehicles and generators manufactured in China that do not comply with environmental requirements.

April 24, 2008
Taiwanese And U.S. Companies Settle Clean Air Violations
A Taiwanese manufacturer and three American corporations will pay a $2 million civil penalty for allegedly importing and distributing approximately 200,000 chainsaws in the U.S. that failed to meet federal air pollution standards, the Justice Department and Environmental Protection Agency announced today. The companies also agreed to spend approximately $5 million on projects to reduce air pollution.

July 10, 2007
Federal Settlement Targets Illegal Emission Control “Defeat Devices” Sold for Autos
WASHINGTON - The Department of Justice and U.S. Environmental Protection Agency (EPA) announced today a landmark settlement requiring Casper’s Electronics, of Mundelein, Ill., to pay a penalty and stop selling devices that allow cars to release excess levels of pollution into the environment, in violation of the Clean Air Act (CAA).

December 21, 2006
Mercedes-Benz Agrees to Pay $1.2 Million Civil Penalty to Settle Clean Air Act Violation
Mercedes-Benz USA and its parent corporation, DaimlerChrysler AG (Mercedes), have agreed to pay $1.2 million in civil penalties to resolve allegations that they violated the Clean Air Act by failing to promptly notify the Environmental Protection Agency (EPA) about defects in the air pollution controls installed on numerous 1998 to 2006 Mercedes model vehicles, the Justice Department and the EPA announced today.

June 15, 2005
Volkswagen of America, Inc. Agrees to Pay Over $1 Million for Clean Air Act Violation
The U.S. Department of Justice and the U.S. Environmental Protection Agency (EPA) today announced a Clean Air Act settlement with Volkswagen of America, Inc. Under the agreement, filed with the U.S. District Court for the District of Columbia, Volkswagen will pay $1.1 million to resolve its failure to promptly notify and correct a defective oxygen sensor affecting at least 326,000 of their 1999, 2000 and 2001 Golfs, Jettas, and New Beetles. This is the largest civil penalty to date for this type of violation.

June 8, 1998
American Honda Agrees to $267 Million Settlement to Resolve Clean Air Act Violations
American Honda Motor Co., Inc. ("Honda") will spend $267 million to settle allegations that it violated the Clean Air Act by selling vehicles with disabled emission control diagnostic systems, the Justice Department, the Environmental Protection Agency, and the California Air Resources Board ("CARB") announced today.

November 30, 1995
U.S. Announces $45 Million Clean Air Settlement with GM. First Judicial Environmental Recall -- 470,000 Cadillacs
General Motors Corporation will spend approximately $45 million to settle government charges that it put illegal devices to defeat pollution controls inside nearly a half-million Cadillacs since 1991 that resulted in carbon monoxide emissions of up to three times the legal limit.


Updated January 3, 2022

Was this page helpful?

Was this page helpful?
Yes No