Indiana engine maker Cummins didn’t admit to wrongdoing in the alleged installation of emissions “defeat devices” on more than 900,000 RAM pickup truck engines over the past decade. The company said it was a defect.

In a press conference on Wednesday, the Environmental Protection Agency and the Department of Justice pushed back on that statement.

The DOJ said the devices cheated emissions tests and allowed diesel engines to pollute the air with nitrogen oxides — which can form harmful smog and particle pollution. This pollution is particularly harmful to children, older adults, people who are active outdoors and those with heart and lung conditions.

David Uhlmann is the assistant administrator of the EPA’s Office of Enforcement and Compliance Assurance. He said Cummins would not be paying more than $1.6 billion — the largest civil penalty in Clean Air Act history — if it did nothing wrong.

“Installing defeat devices on more than 600,000 vehicles over a six year period is wrongdoing. Failing to disclose software on more than 300,000 more vehicles even after they were under investigation is wrongdoing,” Uhlmann said.

READ MORE: Cummins to pay record-setting civil penalty for ‘defeat devices’ in pickup truck engines.

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The DOJ said the settlement and similar ones with Volkswagen, Chrysler and Mercedes-Benz send the message that attempts to cheat emissions tests will not be tolerated.

As part of the settlement, Cummins will recall engine control software in RAM pickup truck engines for model years 2013 through 2019.

Rebecca is our energy and environment reporter. Contact her at rthiele@iu.edu or follow her on Twitter at @beckythiele.