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EPA and California ARB charge Volkswagen with using software defeat device to circumvent NOx testing in 4-cylinder 2.0L diesels

EPA has issued a notice of violation (NOV) of the Clean Air Act (CAA) to Volkswagen AG, Audi AG, and Volkswagen Group of America, Inc. (collectively referred to here as Volkswagen). The NOV alleges that Volkswagen and Audi cars from model years 2009-2015 equipped with 2.0-liter, four-cylinder diesels include software (a “defeat device”) that circumvents EPA emissions standards for NOx. California is separately issuing an In-Use Compliance letter to Volkswagen, and EPA and the California Air Resources Board (ARB) have both initiated investigations based on Volkswagen’s alleged actions.

In response, Volkswagen said that it is cooperating with the investigation, and is unable to comment further at this time. VW may be liable for civil penalties and injunctive relief for the violations alleged in the NOV. The allegations cover roughly 482,000 diesel passenger cars sold in the United States since 2008. Affected diesel models include:

  • Jetta (Model Years 2009 – 2015)
  • Beetle (Model Years 2009 – 2015)
  • Audi A3 (Model Years 2009 – 2015)
  • Golf (Model Years 2009 – 2015)
  • Passat (Model Years 2014-2015)

Volkswagen would need to initiate the process that will fix the cars’ emissions systems. The alleged violations do not present a safety hazard; the cars remain legal to drive and resell. Owners of cars of these models and years do not need to take any action at this time.

As described in the NOV, software installed in the electronic control module (ECM) on the affected vehicles detects when the car is undergoing official emissions testing. EPA calls this software “the switch”.

The switch senses whether the vehicle is being tested or not based on various inputs including the position of the steering wheel, vehicle speed, the duration of the engine’s operation, and barometric pressure. These inputs precisely track the parameters of the federal test procedure used for emission testing for EPA certification purposes. During EPA emission testing, the vehicles’ ECM ran software which produced compliant emissions results under an ECM calibration that VW referred to as the “dyno calibration”. … At all other times during normal vehicle operation, the “switch” was activated and the vehicle ECM software ran a separate “road calibration” which reduced the effectiveness of the emission control system (specifically the selective catalytic reduction or the lean NOx trap). As result, emissions of NOx increased by a factor of 10 to 40 times above the EPA compliant levels, depending on the the of drive cycle.


The software produced by Volkswagen is a “defeat device,” as defined by the Clean Air Act.

The Clean Air Act requires vehicle manufacturers to certify to EPA that their products will meet applicable federal emission standards to control air pollution, and every vehicle sold in the US must be covered by an EPA-issued certificate of conformity. Motor vehicles equipped with defeat devices, which reduce the effectiveness of the emission control system during normal driving conditions, cannot be certified. By making and selling vehicles with defeat devices that allowed for higher levels of air emissions than were certified to EPA, Volkswagen violated two provisions of the Clean Air Act, EPA charged.

ARB and the EPA were alerted to emissions problems with these vehicles in May 2014 when the West Virginia University’s Center for Alternative Fuels, Engines & Emissions published results of a study commissioned by the International Council on Clean Transportation (ICCT) that found significantly higher in-use emissions from a 2012 Jetta and a 2013 Passat. For a year following the publication of the study, VW asserted that the increased emissions could be attributed to various technical issues and unexpected in-use conditions. VW then issued a voluntary recall in December 2014 to deal with the issue.

ARB, coordinating with EPA, conducted follow-up testing, which found only a limited benefit from the recall. ARB then broadened the investigation to determine the technical nature of the poor emissions performance and to figure out why the onboard diagnostics were not detecting the problem.

None of the potential technical issues suggested by VW explained the higher test results consistently confirmed during CARB’s testing. It became clear that CARB and the EPA would not approve certificates of conformity fo VW’s 2016 model year diesel vehicles until VW could adequately explain the anomalous emissions and ensure the agencies that the 2016 model year vehicles would not have similar issues. Only then did VW admit it had designed and installed a defeat device in these vehicles in the form of a sophisticated software algorithm that detected when a vehicle was undergoing emissions testing.


To have a more controlled evaluation of the high NOx observed over the road, CARB developed a special dynamometer cycle which consisted of driving the Phase 2 portion of the FTP repeatedly. This special cycle revealed that VW’s recall calibration did increase Diesel Exhaust Fluid (DEF) dosing upon initial startup; however, dosing was not sufficient to keep NOx emission levels from rising throughout the cycle. This resulted in uncontrolled NOx emission despite the SCR reaching sufficient operating temperatures.

… Several technical meetings with VW followed where VW disclosed that Gen1, Gen2 and the 2015 model-year improved SCR vehicle (known as the Gen3) had a second calibration intended to run only during certification testing. During a meeting on September 3, 2015, VW admitted to CARB and EPA staff that these vehicles were designed and manufactured with a defeat device to bypass, defeat or rend inoperative elements of the vehicles’ emission control system.

—ARB letter


Nick Lyons

Wow. VW is now officially in a world of hurt. Many heads are going to roll from this one, and putting certain corporate decision makers in the slammer would be appropriate.


The story here is the amount of planning and engineering VW used in defeating the rules. I don't know that I would ever buy a car from a company that went to such lengths to cheat. There is a trust issue here as well as a disregard for people's health. Clean diesel is the new clean coal. There is no such thing.


CNBC said the fine could be $18 BILLION.
That is more than $35,000 per car!

Nick Lyons


However, while it is legal to sell the car, CARB and the California Department of Motor Vehicles may not allow the buyer to register the vehicle, and current owners may not be allowed to renew their registrations, until all the emission recall work has been completed. Some states that follow California emission standards (so-called Partial Zero Emission states) also have rules in place that require all emissions-related recalls to be completed before periodical emission testing. If the recall is not completed, the vehicle cannot pass the inspection, and the state will decline renewal of the vehicle registration.

The class-action attorneys are in hurried meetings this afternoon. Every TDI owner is a prospective client.


This makes it sound like some very clever willful fraud and not just some idiot mistake. That is bad. You wonder how high up the chain of command this went. This is not going to be good for VW.


This is just one more fraud fom the ICE vehicle industry. It has been going on the 120+ years. They have ALL done it at one time or another?

Finding a car manufacturer who has not purposely distorted the performance of their poor products is impossible. One has to choose the least guilty, but since facts are never well known, selecting the least fraudulent product is difficult.

From experience, the made in Japan Toyota products gave us the least problems.


35Kper car won't fix the car to the claimed performance though maybe they should have to refund.

False advertising is just another way to steal and is responsible for many honest traders losing market.
That includes distorting the market for hevs and bevs.

This is an embarrassing disclosure of (almost) standard industry practice.

A similar recent consumer protection action against L.G. for false efficiency claims for their fridges.

That behaviour makes me suspicious of their trustworthiness.
Unless they are found out.most consumers have a short memory (if any)

The fact is that official test cycle conditions are at fixed points that can be designed around.

As the various test points are known, it is quite simple to tune for those points to pass even if it is a long way from the average.

If many of these vehicles were tuned to pass the standard from "go to whoa",you wouldn't want to own it.Engines would not perform or last.

Looking at the engine map will show the rpm points corresponding to the test points will show how the engines management system reduce emissions and decibels at those points.

While this is well understood in the motorcycle industry, going the extra step to installing a device shows just how widespread the practice is.

So good on you EPA and don't stop but there are lots of examples of working around the rules.

There are lots of reports and claims of cover ups - not all true.

Toyota's ecu acceleration issues (wrong carpet under the accelerator they claimed for years.)

GM's ignition lock killed hundreds over a decade+

Various makers false fuel efficiency and battery range claims

Air bags anyone?

At least this VW case isn't killing people directly.

The best penalty is name and shame but remember - just because one lot behave like bastards doesn't mean that others don't.


I said here MANY times that diesel is polluting, Is it clear now ?


This is shocking news. I do not have words for it. It is appalling. Hope that VW gets a fine that take back the last 5 or 10 years profits made by VW in the USA. VW needs to understand that this is serious and completely unacceptable.


At second thought I wonder how many other countries than the US that VW have made this deliberate fraud. An investigation into the scale of this needs to be done in everyone of VW markets globally and they should be immediately barred from selling any cars with this pollution fraudster software and a recall should be made immediately for all the cars that are driving in other countries using this software. The probable 18 billion USD fine for the US market could just be the beginning of this outrageous VW scandal.


This is big, deliberately giving intelligence to the control system so as to take the result of anti pollution test is really a gangster idea.. The reputation of Wolskwagen will be badly tarnished by this, I can't believe that the managers of a big company like WV could ho for such nasty tricks, because you can't ignore that sooner or later it will backfire.

Pathetic, after ford and hunday faking the mileage, WV is designing their cars to cheat the antipollution test, unbelievable ...


CARB routinely tests older models of cars that are close to the end of the warranty period on emissions to make sure that the monitors on mode6 and otherwise are working correctly... that and they have tons of data from consumers based on the smog tests.

What we are going to see out of this more likely is a software patch... they'll have to revise power numbers as they'll derate the engine to keep the NOx numbers down.
I don't think it'll be bad enough to resort to adding control devices. NOx is mainly a high cylinder pressure issue. They'll most likely program the issue away.

I personally know a few other makers of Diesel trucks that "cheat the system" through poor detection of faults. I bugged a few cars and they never were able to throw a code for an issue that should have.

Diesel has a very hard time getting in line with emissions.

If everything is working and designed correctly, modern diesels are about as clean as they could get. DPFs do a great job. Cleaner than gasoline even.
This is just criminal, poor engine management system to ignore the law outside of test parameters is inexcusable... the EU is going to have a field day...

I understand that most of you have little experience in the industry, even less formal education on the matter; but could we leave out the libel, slander, and generalizations? Many automakers are good corporate citizens, they play by the rules; sure some faults are intended like this one, some are unforeseen, others are ignored.

I feel any and all discussions would be better if we lost the gross exaggerations and spoke the truth where we could.
I learn so much from the articles and well formed posters on here, I learn a lot from some of those I disagree with. So keep it classy ;)



Sûre we are not all from the car industry, but that doesn't mean we dont kon industry and its rules. In my industry for example we have mandatory trainings for code of conduct and code of ethic, and I am sure they have the same in ten car industry, so how is such choice, as Volkswagen did compatible compatible with good ethic ? The truth is that they understood along the development that they wouldn't pass the régulations with the Kindle of performances they were targeting. So they opted for an illegal trick, across the board, because it affects VW but also Audi, all the board new and signed for it that is pretty clear. And they hav to be punish severely for making that choice the ceo should face criminal charges all the managers who were involved in that decision. You can't let big corporation unpunished when they break the law, because they would be no limits then. I sincerely hope the CEO will go to jail for this


GM said some low level person signed off on the ignition switch..that is a convenient cover, a good system does not allow this. VW may claim the same, which says they have corrupt management that does not want to get caught.

James McLaughlin

There was a story nearly a year ago that sounds very similar:

Perhaps CARB simply found the root cause. From the looks of last year's story, most OEMs had similar "problems". Whether the cause was deliberate or incompetence, I hope it is just the latter. Software gets better slowly, like the people who write it.

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