Tractor maker John Deere faces a federal lawsuit that accuses the company of illegally forcing farmers to use only authorized dealers for critical repairs, boosting its multibillion-dollar profits.

The lawsuit — filed on Wednesday by the Federal Trade Commission along with Illinois and Minnesota — escalates a long-running battle over farmers’ right to repair their own agricultural equipment and parts.

As tractors and combines have gotten more computerized, farmers have complained that Deere has restricted access to its software and made it difficult, or nearly impossible, for owners to diagnose and fix problems themselves or with the help of independent mechanics. Instead, farmers have to use authorized dealers, who tend to charge more and may take longer.