A Cummins ECM is the engine control module of a Dodge Cummins engine. An engine control module is an electronic component that controls the components of internal combustion engines to ensure optimal performance. The module takes input from various sensors, interprets the data and makes adjustments.
One function of a Cummins ECM is to control the amount of air and fuel the engine uses during combustion. The module adjusts the intake to maintain the ideal ratio. The ECM uses data sent by oxygen sensors to determine if the engine is running rich or lean. If the engine is running rich, it means that it is using too much fuel and too little oxygen. If it's running lean, it's using too much oxygen and too little fuel.