Milwaukee-based Harley-Davidson has agreed to pay a civil fine of $12 million in order to settle the Environmental Protection Agency’s claim about selling aftermarket devices which violate air-pollution laws. The announcement was made by the U.S. Justice Department and the motorcycle manufacturer will also have to spend an additional $3 million on an unrelated project with the target to cut air pollution levels.

Under its “Screamin’ Eagle” brand, Harley built and sold around 340,000 ‘super tuner’ devices fitted to motorcycles manufactured since 2008. With the so-called ‘defeat device’ installed, a motorcycle provides better engine performance but at the same time it pollutes the air at a higher level than what it’s mentioned in the certification from EPA. In addition, Harley-Davidson was also found guilty for selling more than 12,600 motorcycles between the years 2006 and 2008 without EPA’s certification concerning emission requirements.

Not only will have to halt sales of its ‘super tuners’ by Tuesday, but the motorcycle manufacturer is also being forced to buy back and destroy all similar devices currently in stock at its dealerships. From now on, Harley will have to get the California Air Resources Board’s certification for any tuners it will want to sell in the United States. For those destined to be sold outside the country, Harley will have to put on a label that says the device is not for use in U.S.

Even though Harley was not ok with EPA’s view regarding the matter, it ultimately decided to settle (without admitting liability) and pay the fine plus the aforementioned $3M as a ‘good faith compromise.’