Lawsuit Accuses GM of Using Defeat Devices in Duramax Diesel Pickups

Suing automakers over diesel emissions violations is quickly on its way to becoming passé.

Since Volkswagen admitted to installing software that circumvented pollution laws, regulators have been on the hunt for their next big target. While it might make their efforts seem like a bit of a witch hunt, there’s good reason to be on the lookout. Studies have shown diesel emission levels are often much higher than analysts expected, with experts attributing the results to the high probability that other automakers are skirting regulatory guidelines — likely by way of defeat devices.

Daimler, Renault, and PSA Group are all being investigated in their home countries as FCA faces legal action within the United States.

General Motors is now being sued for allegedly installing defeat devices in its trucks to sidestep emissions tests, making it the sixth major manufacturer accused of diesel cheating since 2015. However, General Motors isn’t dabbling in gray areas, acting confused, or assuring the public it will get to the bottom of the accusations. It says the claims against it are flat out wrong.

Pat Morrissey, director of corporate communications at GM, issued a concise two-sentence response after news of the lawsuit broke. “These claims are baseless and we will vigorously defend ourselves,” Pat Morrissey stated. “The Duramax Diesel Chevrolet Silverado and GMC Sierra comply with all U.S. EPA and CARB emissions regulations.”

Owners and lessees of some 705,000 pickups powered by Duramax diesels filed a class-action lawsuit on Thursday, claiming GM had installed defeat devices in Chevrolet Silverados and GMC Sierras from 2011 through 2016. According to Bloomberg, it’s their assertion that the automaker misrepresented the Duramax’s abilities and that the system produces two to five times the legal limit of pollutants under normal driving conditions.

“GM claimed its engineers had accomplished a remarkable reduction of diesel emissions,” attorney Steve Berman said in the formal complaint. “These GM trucks likely dumped as much excess poisonous emissions into our air as did the cheating Volkswagen passenger cars.”

Berman is also currently representing drivers and dealerships in the litigation against FCA and previously went up against Volkswagen before it was slapped with $24.5 billion worth of penalties, fines, and vehicle recalls. Another similar thread between the cases is the inclusion of German auto supplier Bosch.

In the case against General Motors, Bosch is named as a defendant involved in the installation of three separate defeat devices, particularly those relating to the emission of nitrogen oxide pollutants. However, GM has already disclosed numerous on-board devices that help mitigate NOx levels, all of which have received EPA approval. Among the most noteworthy are the Duramax’s selective catalyst reduction system and treated diesel exhaust fluid (DEF), both of which serve to reduce NOx emissions. Both are standard items on modern diesel trucks and have proven to be one of the better ways to adhere to emissions guidelines without sacrificing performance.

As the name suggests, the catalyst reduction system is selective and not perpetually active — meaning there are occasions where emission levels can fluctuate outside of prescribed levels (when the vehicle is warming up, for example). Adequate levels of DEF are also required for the process to convert NOx into nitrogen gas and water. Without it, the truck’s computer eventually forces it to run in a more lethargic mode and may eventually forbid the vehicle from restarting.

In addition to this, Duramax-powered vehicles have a Regen mode that serves to burn off soot accumulated in the diesel particulate filter (DPF). During the process, fuel is injected into the exhaust in order to raise exhaust gas temperatures high enough to clear the DPF.

[Image: General Motors]