Over the course of a decade, hundreds of thousands of Ram 2500 and 3500 heavy duty pickup trucks – manufactured by Stellantis – had Cummins diesel engines equipped with software that limited nitrogen oxide pollution during emissions tests but allowed higher pollution during normal operations, the governments alleged.

In all, about 630,000 pickups from the 2013 through 2019 model years were equipped with the so-called “defeat devices” and will be recalled. Roughly 330,000 more trucks from 2019 through 2023 had emissions control software that wasn’t properly reported to authorities, but the government says those didn’t disable emissions controls. Officials could not estimate how many of the recalled trucks remain on the road.

Stellantis deferred comment on the case to Cummins, which has denied allegations made by the government and is not admitting liability, according to court documents.

The engine maker said in a statement that Wednesday’s actions do not involve any more financial commitments than those announced in December. “We are looking forward to obtaining certainty as we conclude this lengthy matter and continue to deliver on our mission of powering a more prosperous world,” the statement said.

Cummins also said the engines that were cited but are not being recalled did not exceed emissions limits. Punishment for the unreported software is included in the penalty, the company said.

As part of the settlement, Cummins will make up for smog-forming pollution that resulted from its actions.

Preliminary estimates suggested its emissions bypass produced “thousands of tons of excess emissions of nitrogen oxides,” U.S. Attorney General Merrick B. Garland previously said in a prepared statement.

The Clean Air Act, a federal law enacted in 1963 to reduce and control air pollution across the nation, requires car and engine manufacturers to comply with emission limits to protect the environment and human health.

The transportation sector is responsible for about one-third of U.S. greenhouse gas emissions, and much of that stems from light-duty vehicles. Limits aim to curb the amount of emissions from burning gasoline and diesel fuel, including carbon dioxide and other problematic pollutants.

“We increasingly are finding that the public health impacts from emissions from cars are really devastating and it is one of our biggest sources also of emissions leading to climate change,” said Jacqueline Klopp, director of the Center for Sustainable Urban Development at the Columbia Climate School.

“To the extent that vehicle manufacturers are trying to evade our emission standards that are our biggest tool for protecting us from these public health impacts and climate change, these kinds of fines for evasion are hopefully a very important deterrent,” she added. “There are profound justice and equity issues around air pollution produced by transport emissions.”

Diesel exhaust is harmful to human health; it’s a carcinogen. Long-term exposure to ozone-creating nitrogen oxides can cause health issues like respiratory infections, lung disease, and asthma.

Officials said Wednesday it was not lost on them that the Cummins settlement follows several other notable emissions cheating cases involving the auto industry in recent years.

Wednesday’s details come seven years after German automaker Volkswagen agreed to plead guilty to criminal felony counts following investigations into its use of similar defeat devices, a massive emissions scandal known as Dieselgate.

The company installed software in certain model year 2009-2015 diesel vehicles across its brands, circumventing emissions standards and emitting up to 40 times more pollution than those standards allow. Volkswagen said 11 million vehicles across the globe were equipped with the pollution controls.

In 2017, the automaker agreed to pay a $2.8 billion criminal penalty in addition to $1.5 billion in separate civil resolutions.

Fiat Chrysler saw similar consequences in 2019 for failing to disclose defeat devices used to make vehicle emission control systems function differently during emission testing. More than 100,000 EcoDiesel Ram 1500 and Jeep Grand Cherokee vehicles were sold in the U.S. with the unauthorized software.

The automaker agreed to pay a $305 million civil penalty to settle the claims of cheating emission tests in 2019.

In 2020, Daimler, the auto parent of Mercedes-Benz, agreed to a $857 million civil penalty as a result of its disclosure failures and claims over its violations of the Clean Air Act.

“There’s a lot of sunk money into diesel engines and people making profits off of diesel engines,” Columbia’s Klopp said. “Unless you give them a really big fine and a really big deterrent, they’re willing to pay the fines to get those profits. That’s really sad because it puts the profits before the health of our communities.”

Alexa St. John is an Associated Press climate solutions reporter. Tom Krisher is Associated Press auto writer.