A GM Duramax diesel emissions lawsuit has been filed for owners and lessees of 2011-2016 Chevrolet Silverado Duramax and GMC Sierra Duramax diesel trucks that allegedly emit too much nitrogen oxides.
The General Motors lawsuit alleges the automaker rigged the trucks to pass emissions tests while emitting illegal nitrogen oxide levels on the roads.
Attorneys say the trucks emit up to five times the legal limits of nitrogen oxides during normal driving by using "defeat devices" that keep the emissions legal in a lab setting.
The Silverado and Sierra allegedly have three devices which alter the emissions controls during official testing. In comparison to Volkswagen's confirmed defeat devices that caused millions of vehicles to emit up to 40 times the legal levels of nitrogen oxides, the accusations against GM seem minor.
However, attorneys say their testing shows the trucks are illegal, a claim that could affect more than 700,000 trucks in the U.S.
According to the Duramax lawsuit, the defeat devices alter the emissions controls at temperatures above 86 degrees Fahrenheit, the upper limit for emissions certification testing, and again below 68 degrees Fahrenheit, the lower limit for emissions certification testing.
The suit says the temperature-based defeat devices combine to de-rate emissions controls during 65 to 70 percent of the miles the trucks are driven in and around the 30 largest population centers in the U.S.
In addition to GM, the Duramax lawsuit names parts manufacturer Bosch as a defendant that allegedly worked with GM in manufacturing the electronic diesel control units that allowed GM to activate the defeat devices. The lawsuit against Bosch will be nothing new to the company after the supplier was punished for jumping into bed with Volkswagen.
The GM lawsuit alleges that even if the automaker can fix the allegedly illegal emissions to bring them compliant with federal standards, the fix could reduce power, torque and fuel efficiency. However, the automaker was quick to release a statement in response to the Duramax diesel lawsuit.
"These claims are baseless and we will vigorously defend ourselves. The Duramax Diesel Chevrolet Silverado and GMC Sierra comply with all U.S. EPA and CARB emissions regulations." - General Motors
The GM Duramax diesel lawsuit was filed in the U.S. District Court for the Eastern District of Michigan in Detroit by Hagens Berman, the same legal team who prosecuted Volkswagen in its emissions scandal.
Attorneys for Hagens Berman also filed a separate lawsuit against General Motors in 2016 alleging 2014 Chevy Cruze cars are equipped with illegal emissions defeat devices. A federal judge dismissed some of the claims while allowing certain claims to continue, which is where the lawsuit stands to date.
Another GM Duramax diesel emissions lawsuit was filed by different attorneys in 2015 that also includes the Chevrolet Silverado and GMC Sierra, plus the Chevy Express and GMC Savana.
The lawsuit alleges when the vehicles move at slow speeds for long periods of time, drivers are told to drive faster to make the exhaust hotter so it can clean the diesel particulate filter. However, GM allegedly made changes to the diesel engines to get around the problem, but those changes caused decreased fuel efficiency.