VW, Audi Diesels Circumvented Clean-Air Regs

Audi and Volkswagen four-cylinder diesels used software to circumvent federal emissions standards, the U.S. Environmental Protection Agency has alleged.

by Staff

September 18, 2015

VW, Audi Diesels Circumvented Clean-Air Regs — *Photo of 2015 Golf TDI engine courtesy of VW.*

1 min to read

*Photo of 2015 Golf TDI engine courtesy of VW.*

Audi and Volkswagen four-cylinder diesels used software to circumvent federal emissions standards, the U.S. Environmental Protection Agency has alleged.

The cars from the 2009 to 2015 model years included a "defeat device" — a sophisticated software algorithm that detects when the car is undergoing official emissions testing and turns on full emissions controls during that test, according to an EPA violation notice issued Sept. 18. This would violate the Clean Air Act.

The allegations cover about 482,000 models, including the Jetta TDI, Beetle TDI, Golf TDI, and Audi A3 TDI. The Passat TDI is affected from the 2014-MY and 2015-MY.

“Using a defeat device in cars to evade clean air standards is illegal and a threat to public health,” said Cynthia Giles, assistant administrator for the EPA's Office of Enforcement and Compliance Assurance.

In a separate action, the California Clean Air Resources Board has issued an In-Use Compliance letter. CARB has initiated its own investigation in addition to the EPA probe.

"Our goal now is to ensure that the affected cars are brought into compliance, to dig more deeply into the extent and implications of Volkswagen's efforts to cheat on clean air rules, and to take appropriate further action," said Richard Corey, CARB executive officer.

By using the defeat device, the cars will emit nitrogen oxides (NOx) at up to 40 times the regulatory standard during normal operating conditions, according to the EPA.

Volkswagen must now offer a fix for affected models, which remain legal to drive and resell. Volkswagen had not commented publicly on Sept. 18.

EPA and CARB uncovered the defeat device software after independent analysis by researchers at West Virginia University, working with the International Council on Clean Transportation, a non-governmental organization, raised questions about emissions levels. The agencies began further investigations into the issue. In September, after EPA and CARB demanded an explanation for the identified emission problems, Volkswagen admitted that the cars contained defeat devices, according to EPA.

Read the EPA's full release here.

Topics:Clean Air Act CARB Volkswagen Emissions 2009-MY Audi VW Diesel Scandal EPA 2015-MY Green Fleet

More Green Fleet

Hybrids: Electrification Without the Challenges

For fleet managers, fuel is one of the biggest line items in the budget — and it's one hybrids can shrink without changing how your people work. Download the eBook to see the numbers, understand the technology, and get a step-by-step guide to making the switch.

Green Fleet•by Chris Brown•March 9, 2026

Startup ZMD Motors Developing Electric Conversion for Ram 5500 Work Trucks

Detroit-based company says it has begun early development of a system to convert internal combustion Ram 5500 chassis-cab trucks to electric power.

MOVING ON FROM DEBATE: A Guide for Fleet Managers Who Just Want To Get Electrification Done

Fleet managers are done with the debate—and focused on execution. Learn how to build a practical electrification strategy that aligns infrastructure, operations, and financing while keeping costs controlled and deployment scalable with support from Blink Charging. Discover how smart planning today positions fleets for long-term performance and ROI.