What is the purpose of the oxygen (O2) sensor in small engines?

The purpose of the oxygen sensor in small engines is primarily to monitor the amount of oxygen present in the exhaust gases. By analyzing this information, the sensor plays a crucial role in determining the fuel burn efficiency. A properly functioning oxygen sensor allows the engine management system to adjust the air-fuel mixture accordingly, optimizing combustion. This adjustment ensures that the engine runs efficiently, produces minimal emissions, and operates smoothly under various conditions.

In contrast, other options refer to functions that are not within the primary duties of an oxygen sensor. Monitoring carbon dioxide levels, controlling throttle positions, or measuring engine coolant temperature involve different sensors and systems that each address their respective aspects of engine function and performance.