What is the primary role of the oxygen sensor in engine operation?

The oxygen sensor plays a crucial role in monitoring the amount of oxygen present in the exhaust gases emitted by the engine. This measurement is key for the engine control module (ECM) to optimize the air-fuel mixture for combustion. When the oxygen sensor provides feedback about the oxygen levels, the ECM can adjust the fuel injection to ensure that the engine runs efficiently, minimizes emissions, and achieves the best performance.

This feedback loop is vital for maintaining the correct stoichiometric ratio—the ideal ratio of air to fuel for combustion—enabling the engine to operate efficiently across various conditions. By ensuring that the air-fuel mixture is neither too rich nor too lean, the oxygen sensor helps in controlling emissions and improving fuel economy.