WASHINGTON (CBSNewYork/AP) — The Environmental Protection Agency on Friday ordered Volkswagen to fix nearly 500,000 VW and Audi diesel cars that the agency said are intentionally violating clean air laws by using software that evades EPA emissions standards.

VW, which owns Audi, faces billions of dollars in fines, although exact amounts were not determined.

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The cars, all built in the last seven years, include a device programmed to detect when they are undergoing official emissions testing, the EPA said, adding that the cars only turn on full emissions control systems during that testing. The controls are turned off during normal driving situations, the EPA said.

The EPA called the company’s use of the device illegal and a threat to public health.

The EPA called on VW to fix the cars’ emissions systems, but said car owners do not need to take any immediate action. The violations do not present a safety hazard and the cars remain legal to drive and sell, the EPA said.

The German automaker said in a statement it is cooperating with the investigation, but declined further comment.

The EPA said VW faces fines of up to $37,500 per vehicle for the violations — a total of more than $18 billion. No final total was announced.

Despite the seriousness of the violation, the EPA said VW will be given “a reasonable amount of time to develop a plan to complete the repairs,” including both the repair procedure and manufacture of any needed parts.

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It could take up to a year to identify corrective actions, develop a recall plan and issue recall notices, the EPA said.

The allegations cover roughly 482,000 diesel passenger cars sold in the United States since 2008. Affected models include:

. Jetta (Model Years 2009 – 2015)

. Beetle (Model Years 2009 – 2015)

. Audi A3 (Model Years 2009 – 2015)

. Golf (Model Years 2009 – 2015)

. Passat (Model Years 2014-2015)

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