The Environmental Protection Agency is accusing Fiat Chrysler Automobiles NV of using software to bypass standard emissions regulations.
The EPA said Thursday that the automobile maker allowed excess diesel emissions in 104,000 U.S. trucks and SUVs sold since 2014, a discovery that was uncovered after an EPA investigation into Fiat's competitor Volkswagen.
The government agency said that FCA used engine management software that it did not disclose and that the undisclosed software resulted in increased emissions of nitrogen oxides from the vehicles. The EPA is still investigating and has not concluded whether the undisclosed software would be considered a "defeat device" meant to get around emissions standards.
The EPA added that no immediate consumer actions are necessary and that the vehicles are still safe and legal to drive.
Affected vehicles include 2014-2016 year models of Jeep Grand Cherokee and Dodge Ram 1500 trucks with 3.0-liter diesel engines, Reuters reported.
EPA official Cynthia Giles said in a statement: "Failing to disclose software that affects emissions in a vehicle’s engine is a serious violation of the law, which can result in harmful pollution in the air we breathe."
California Air Resource Board Chairwoman Mary Nichols added: "Once again, a major automaker made the business decision to skirt the rules and got caught.”
FCA denied the allegations in a statement Thursday, stating that it is "disappointed" in the claims of wrongdoing on their part. The organization added they would prove that their software was "properly justified and thus are not 'defeat devices' under applicable regulations."
“FCA U.S. intends to work with the incoming administration to present its case and resolve this matter fairly and equitably and to assure the EPA and FCA U.S. customers that the company’s diesel-powered vehicles meet all applicable regulatory requirements,” the statement said.
Fiat Chrysler saw their stock price drop as low as 18 percent as soon as news broke Thursday morning.
The news came only days after federal prosecutors announced a settlement with the automaker Volkswagen after it was discovered in September 2015 that the company deliberately cheated on emissions tests. Volkswagen has pleaded guilty to defrauding regulators and consumers and is facing up to $20 billion in fines.