UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K-A CURRENT REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): December 1, 2003 CLEAN DIESEL TECHNOLOGIES, INC. (Exact name of registrant as specified in its charter) DELAWARE 000-27432 06-1393453 (State or other jurisdiction (Commission (IRS Employer of incorporation) File Number) Identification No.) SUITE 702, 300 ATLANTIC STREET STAMFORD CT 06901 (203) 327-7050 (Address and Telephone Number of principal executive offices) ITEM 7. FINANCIAL STATEMENTS, PROFORMA FINANCIAL INFORMATION AND EXHIBITS. (c) Exhibits. Exhibit 16.1 Description: Letter, dated December 4, 2003, from Ernst & Young LLP to the Securities and Exchange Commission. SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. Clean Diesel Technologies, Inc. By: /s/ D.W. Whitwell ------------------- David W. Whitwell Vice President, Treasurer & Chief Financial Officer