California Air Resources Board

This Manufacturers Advisory Correspondence (MAC) provides guidance to manufacturers regarding the implementation of an engine shutdown system (ESS) that complies with California requirements. An ESS is required on all new 2008 and subsequent model year California-certified heavy-duty diesel engines (Gross Vehicle Weight Rating greater than 14,000 pounds) pursuant to Section 1956.8 of Title 13, California Code of Regulations, which became effective on November 15, 2006 following the Board’s adoption on October 20, 2005.