The justice department filed suit against German automaker Monday, claiming the company deliberately cheated on emissions tests affecting as many as 600,000 vehicles sold in the US the action exposes the company to billions of dollars in penalties for violating clean air quality standards. Last September Volkswagen admitted it had installed “defeat” codes in car computers that turned on pollution controls when the car was tested, but then shut down controls when it returned to “real world” driving. The e-p-a says cheating vehicles actually chug out as many as 40 times the level of harmful gases regulated by federal law. Volkswagen has blamed a small group of engineers for the scandal and says top management had no idea pollution results were tampered with. Volkswagen says it will fix the cars with faulty diesel engines and compensate owners for a drop in resale value. Offending models include the Passat made in Chattanooga.