The New York Times reports Volkswagen has been ordered by the Environmental Protection Agency to recall 482,000 diesel cars in the U.S. over software they say was intentionally designed to circumvent smog regulations. (See updates below, but no recalls yet.)

The cars, all diesels from 2009 to 2015, have a “defeat device” programmed to detect when the car is undergoing official emissions testing that only then turns on the full emissions control systems, the Times reports.

These controls are turned off in other situations, leading to far greater emissions than VW let on — which is against the law. The devices were designed to conceal nitrogen oxide emissions.

It’s not immediately clear why VW had such a system on these cars, how the system detected official testing versus normal driving, or if the cars operated differently in normal driving when the defeat device was off. What effect did reducing NOx emissions have on fuel economy or performance?

“Using a defeat device in cars to evade clean air standards is illegal and a threat to public health,” said Cynthia Giles, the E.P.A.’s assistant administrator for the Office of Enforcement and Compliance. “Working closely with the California Air Resources Board, E.P.A. is committed to making sure that all automakers play by the same rules. E.P.A. will continue to investigate these very serious violations.”

The state of California and the Justice Department are also investigating the violation, the paper reports.

Advertisement

The vehicles affected are the 2009-2015 diesel Jetta, Beetle, Golf, Passat and Audi A3.

More on this as we get it.

Update: An earlier version of this story, based on incorrect news reports, said VW was ordered to recall the cars. That is not true, at least not yet. Via Automotive News:

Janet McCabe, acting assistant administrator for the EPA’s Office of Air & Radiation, said that the agency will “hold VW responsible” for recalling the affected vehicles to reduce the excess emissions, but said no recall order was issued as part of today’s announcement.

No fines or recalls have been ordered but the investigation continues.

AN reports the EPA discovered the issue after an independent analysis and extensive lab testing. Indeed, the cheat device was present on all VW diesels, not just the ones used for EPA testing. When it is not working, the cars emit 40 times more than the allowable levels of emissions.

Contact the author at patrick@jalopnik.com.