Consumers Sue General Motors for Allegedly Installing Multiple Emissions-Cheating Defeat Devices in Over 705,000 Duramax Diesel Trucks

Class-action lawsuit says GM knowingly sold trucks that are rigged to pass emissions tests, yet in real world driving emit 2 to 5 times the legal limit of dangerous NOx pollutants

DETROIT – Consumers are suing General Motors for allegedly rigging the emissions controls in Duramax diesel trucks in order to pass emissions tests, while in real world conditions the trucks emit 2 to 5 times the legal limits of deadly NOx pollutants, according to Hagens Berman.

The lawsuit states that GM did so all to increase the vehicles’ power and efficiency, and thus the appeal of its best-selling pick-up trucks. The complaint identifies and describes three distinct “defeat devices,” which turn down or “de-rate” the emissions controls in place compared to when the vehicles are in a testing environment.

Vehicle owners are represented by leading auto defect consumer-rights law firm, Hagens Berman, which has been involved in many of the largest automotive settlements in U.S. history, including the $10 billion Volkswagen diesel emissions settlement, the $1.3 billion Volkswagen dealer settlement and the $1.6 billion consumer settlement against Toyota. Based on its testing of emissions control systems, the firm is also leading litigation against Chevrolet, Fiat-Chrysler and Mercedes for illegal use of emissions-cheating software. The level of excess NOx emissions from GM trucks is 2 to 5 times the legal limits, and there are estimated to be at least 705,000 of these big trucks on the road.

If you own or lease a 2011-2016 Chevrolet Silverado Duramax diesel or a GMC Sierra Duramax diesel, you may be entitled to participate in the litigation involving this alleged fraud. Making these trucks EPA and CARB compliant, if possible, could increase the frequency of active regeneration cycles, and may reduce power, torque and fuel efficiency. Contact Hagens Berman to find out more about this issue and your consumer rights against GM.

The complaint, filed on May 25, 2017, in the U.S. District Court for the Eastern District of Michigan (Detroit) states that roughly 705,000 Silverado and Sierra diesels are on the road. It alleges: “Increased sales and thus increased profits drove GM to use at least these three defeat devices in its Duramax diesel engines. By reversing the traditional order of the exhaust treatment components and putting the Selective Catalytic Reduction (“SCR”) in front of the Diesel Particulate Filter (“DPF”), GM could obtain and market higher power and efficiency from its engines while still passing the cold-start emissions certification tests. This made GM’s trucks more appealing and competitive in the marketplace, driving up sales and profits.”

But as Hagens Berman managing partner Steve Berman explained, “Putting the SCR in front of the DPF drastically increases the need for Active Regeneration of the DPF and other power and efficiency sapping exhaust treatment measures, which would reverse the competitive edge gained. Rather than take the time to design a system that could actually pass emissions and provide the characteristics GM sought, GM’s solution was to install defeat devices to provide maximum pollution control in testing environments, while reducing SCR dosing, increasing NOx emissions, and thus decreasing fuel and power-sapping Active Regeneration during regular driving. GM turned a blind eye to the drastic increase in deadly NOx emissions its scheme caused--all to drive up its sales and profits.”

“GM claimed its engineers had accomplished a ‘remarkable reduction of diesel emissions,’” the lawsuit states, citing GM’s promises that the GMC Sierra and Chevy Silverado Duramax engines turned “heavy diesel fuel into a fine mist,” and delivered “low emissions, that were a ‘whopping reduction’ from the prior model.” But the suit states that during on-road testing these diesel trucks pollute at levels well beyond legal limits, many times higher than their gasoline counterparts, and far in excess of what reasonable consumers would expect.

The alleged defeat devices combine to de-rate and degrade emissions controls: (1) above 86 degrees Fahrenheit—the upper limit for emissions certification testing; (2) below 68 degrees Fahrenheit—the lower limit for emissions certification testing; and (3) after 200 to 500 seconds of study driving—a scenario that never happens during certification emissions tests. When this third defeat device is active, emissions increase on average by a factor of 4.5. As a result, the trucks appear to comply with emissions regulations when they are being tested, but otherwise gain power and efficiency by dumping vast quantities of deadly NOx into the air we all breathe. As alleged in the complaint, the temperature-based defeat devices combine to de-rate emissions controls during 65 to 70 percent of the miles the vehicles are driven in and around the 30 largest population centers in the United States.

The suit also names Bosch as a defendant, adding that “GM did not act alone.” Bosch developed, manufactured, and tested the Electronic Diesel Control unit that allowed GM to implement the defeat devices, according to the suit. And Bosch control units are found in almost all of the vehicles found or alleged to have been manipulating emissions, including Mercedes, Fiat Chrysler and Chevrolet.

“GM sold its Duramax line as a powerful diesel that magically emitted lesser amounts of harmful NOx pollutants,” Berman said. “But as our firm’s testing revealed, GM could not accomplish what it promised consumers. Instead, it used complex devices to mask its vehicles’ output of emissions, cheating emissions test, cheating purchasers, and putting all of us at risk of increased respiratory illness.”

Hagens Berman’s automotive legal team has dedicated substantial resources to uncovering cheating devices used by automakers. The firm has become a trailblazer in this highly specialized realm, outpacing federal and state agencies in unmasking fraud in emissions reporting.

Hagens Berman’s managing partner, Steve Berman, has dedicated the firm’s resources to upholding the rights of consumers and protecting our environment. The firm is uniquely dedicated to this cause, and is the only firm that has purchased and deployed an on-road emission testing machine to determine if other diesel car manufacturers install similar cheating devices, bringing new cases based on the firm’s own research, time and testing.

Learn more about the latest class-action lawsuit against GM for its emissions cheating in Chevy Silverado and GMC Sierra diesel vehicles.


About Hagens Berman
Hagens Berman Sobol Shapiro LLP is a consumer-rights class-action law firm with offices in 10 cities. The firm has been named to the National Law Journal’s Plaintiffs’ Hot List eight times. More about the law firm and its successes can be found at Follow the firm for updates and news at @ClassActionLaw.


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