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WASHINGTON, May 23 (Reuters) - The U.S. government plans to file a civil lawsuit on Tuesday accusing Fiat Chrysler Automobiles NV of using software to bypass emission controls in diesel vehicles, two sources briefed on the matter said.
The U.S. Justice Department lawsuit, expected to be filed in Detroit, will say the Italian-American automaker placed undeclared "defeat devices," or auxiliary emissions controls, in 2014-2016 Fiat Chrysler diesel vehicles, the sources said.
Fiat Chrysler did not immediately comment. Its shares fell 3 percent in the minutes after Reuters' report of the suit.
In January, the U.S. Environmental Protection Agency and California accused Fiat Chrysler of illegally using undisclosed software to allow excess diesel emissions in 104,000 U.S. 2014-2016 Jeep Grand Cherokees and Dodge Ram 1500 trucks.
Fiat Chrysler said on Friday it plans to update software that it expects will resolve the concerns of U.S. regulators about excess emissions in those vehicles.
The January notice was the result of regulators' investigation of rival Volkswagen AG's excess emissions.
Fiat Chrysler has applied for certification to sell 2017 diesel models from U.S. and California regulators and said it was in talks to win approval for a software update to address regulators' concerns about emissions in vehicles on the road.
The software update would begin rolling out once the EPA and California Air Resources Board approved it, Fiat Chrysler said Friday. The company said it does not anticipate any impact on performance or fuel efficiency.
Reuters reported on May 17 that the Justice Department was preparing to file a civil lawsuit against the automaker.
A federal judge in California set a Wednesday hearing on a series of lawsuits filed by owners of vehicles and some dealers against Fiat Chrysler. (Reporting by David Shepardson; Editing by Jeffrey Benkoe and Nick Zieminski)