The road continues to get bumpy for Volkswagen as a new civil suit filed by the U.S. Justice Department could mean the ramping up of legal action against the company.

On Monday the Department of Justice (DOJ) filed a civil complaint against Volkswagen saying the German automaker installed illegal devices on almost 600,000 diesel engine vehicles which would fake emissions readings allowing them to pass Environmental Protection Agency (EPA) standards. The DOJ filed the suit on behalf of the EPA which said the devices violated the Clean Air Act and are responsible for producing harmful air pollution.

The suit is in response to the emissions-cheating scandal involving Volkswagen which began in September. The company admitted to the “irregularities” after the EPA issued a notice of violation.

The suit, filed Monday in federal court in Detroit, does not involve any criminal charges, nor does it call out any executives or corporate heads, but the New York Times reports that many public health and environmental advocates are pushing the government to follow up with more serious charges.

“The government should follow up with criminal charges against both VW and its management to protect our health from auto pollution and signal other automakers that it will throw the book at any company that follows VW’s lead,” Dan Becker, director of the safe-climate campaign at the Center for Auto Safety, wrote in an email.

In a statement on the suit, the DOJ said a civil complaint “does not preclude the government from seeking other legal remedies.” California and the DOJ both have investigations ongoing and both are working the with EPA.

While the suit does not have any list of actions that the company must take or what potential fines could be, a story on CNNmoney.com said the EPA will seek fines of up to $37,500 per car and $3,750 for “piece of equipment that was put there to cheat emissions tests.”

Volkswagen continues to say it will “cooperate with the EPA” and in November began offering “goodwill packages” to customers.

Here is an EPA list of the cars that are affected by the scandal.