Fiat Chrysler may have a plan to address EPA complaints regarding software in its 3.0-liter EcoDiesel V-6, according to comments by CEO Sergio Marchionne.

The EPA announced earlier this month that Fiat Chrysler Automobiles had failed to disclose eight separate software routines that affect the engine's emissions, each of which is a violation of the Clean Air Act.

However, the agency has not thus far declared any of the eight undisclosed auxiliary emission-control devices, or AECDs, to be illegal "defeat devices."

DON'T MISS: EPA says Ram, Jeep diesel emission software violates Clean Air Act (updated)

But it is still investigating the AECDs, installed in roughly 100,000 Ram 1500 EcoDiesel full-size pickup trucks and Jeep Grand Cherokee EcoDiesel SUVs from model years 2014 through 2016.

FCA is in "pretty intense discussions" with both the EPA and the California Air Resources Board (CARB) over the EPA allegations, Marchionne said during a conference call with financial analysts and media last week, according to The Detroit News.

He said the talks were progressing well, and that FCA expected to have its EcoDiesel vehicles certified for the 2017 model year "relatively quickly."

2014 Ram 1500 EcoDiesel, Bear Mountain, May 2014

2014 Ram 1500 EcoDiesel, Bear Mountain, May 2014

As for vehicles already on the road, FCA could "simply" re-flash their engine control units to bring the software into compliance, Marchionne reportedly said.

The FCA CEO has denied that any illegal software is present in these vehicles, and added that anyone drawing a comparison between the complaint against FCA and the Volkswagen diesel scandal is "smoking illegal material."

ALSO SEE: Justice Department launches criminal probe of FCA diesels: report

The majority of the Volkswagen diesel scandal focused on the deliberate installation of "defeat device" software 2.0-liter TDI 4-cylinder diesels that changed their behavior whenever they detected they were not undergoing emissions tests.

VW was also investigated for not disclosing three AECD routines—the same type of software FCA is being investigated over—in its 3.0-liter V-6 diesels. One of those routines was found to be a "defeat device."

2014 Jeep Grand Cherokee EcoDiesel, Catskill Mountains, NY, Jan 2014

2014 Jeep Grand Cherokee EcoDiesel, Catskill Mountains, NY, Jan 2014

Marchionne has been a staunch advocate of the use of diesel engines to meet both U.S. and European fuel-economy standards.

But more recently, he has said the added costs of making diesel compliant with stricter versions of these standards may soon make them impractical.

MORE: Cost to make FCA diesels emission-compliant in Europe: half a billion dollars

At a press conference held January 9—two days before the EPA announced its "notice of violation" against FCA—Marchionne said the cost of transitioning 80 percent of FCA's diesels to new Euro 6 standards would cost $531 million.

That could make diesels financially nonviable, and force a shift toward plug-in electric cars, Marchionne said.

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