This document describes the application of the SAE J1939 recommended practices for compliance with on-board diagnostic malfunction detection system requirements for marine sterndrive and inboard spark ignition engines, as mandated by the California Air Resources Board (CARB). These Otto-cycle engines are not derived from automotive diesel-cycle engines. The purpose of this recommended practice is to provide a standard open interconnect architecture that allows a generic diagnostic tool to communicate with marine sterndrive and inboard spark ignition engine's on board diagnostic system. These on-board diagnostic malfunction detection system requirements are referred to as OBD-M in this document.