Volkswagen has one month to come up with a plan on how to fix nearly 500,000 diesel-engine vehicles that contain “defeat devices” to skirt federal emissions standards, a judge overseeing class-action suits against the carmaker declared on Thursday.

The Associated Press reports that U.S. District judge Charles R. Breyer gave VW until March 24 to provide him with a report on available solutions for the issue and how it plans to compensate owners of the affected vehicles.

VW admitted in September that it had used illegal software – which disables air-emissions controls during normal driving conditions – in 11 million vehicles around the world after the Environmental Protection Agency and California Resources Board found defeat devices in more than 500,000 cars in the U.S.

Under the Clean Air Act, vehicle manufacturers are required to certify to the EPA that their products will meet applicable federal emission standards to control air pollution, and every vehicle sold in the U.S. must be covered by an EPA-issued certificate of conformity.

Judge Breyer said on Wednesday that six months is long enough for VW to find a solution to the issue, emphasizing that every day the cars remain in use additional pollution is emitted.

“It’s an ongoing harm that has to be addressed,” Breyer said. “I’ve found the process is a function of how much time people have available to fill. The story about lawyers is that if you give them a year to do something, it will take them a year to do something. If you give them 30 days to do something, they’ll do something in 30 days.”

A spokesperson for VW tells the AP that the company is working “as quickly as possible” to find a solution.

VW’s road to fixing the vehicles hasn’t already been easy.

The California Air Resources Board rejected VW’s proposal to fix 2-liter sedans sold in California between 2009 and 2015 in mid-January, calling the plan “incomplete, substantially deficient, and fall far short of meeting the legal requirements to return these vehicles to the claimed certification configuration.”

VW submitted another plan for its 3-liter vehicles affected in California on Feb. 2, CARB has 30 days to review that proposal.

Judge to VW: Find a fix quick for dirty diesel cars [The Associated Press]

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