Engine manufacturer Navistar International is under investigation by the U.S. Securities and Exchange Commission on suspicions it committed fraud in seeking Environmental Protection Agency certification in 2012, and now the SEC has charged that the company is improperly withholding certain records, asking a judge to force it to release more information. Lisle, Illinois-based Navistar claims the records, mainly communications between the company and both law firms and public relations firms , are privileged, Reuters reported.