What is the primary function of an O2 sensor?

The primary function of an O2 sensor is to measure the oxygen content in exhaust gases. This sensor plays a critical role in the vehicle's emissions control system by providing feedback to the engine control unit (ECU) about the air-fuel mixture being burned in the engine. By monitoring the levels of oxygen in the exhaust, the O2 sensor helps the ECU make adjustments to optimize the combustion process, ensuring that the engine runs efficiently and produces fewer emissions.

When the O2 sensor detects that the exhaust gas has either too much oxygen (indicating a lean mixture) or not enough (indicating a rich mixture), it sends this information to the ECU. The ECU can then adjust the fuel injection and air intake to achieve the ideal air-fuel ratio. This process not only enhances engine performance but also plays a significant role in compliance with environmental regulations by minimizing harmful emissions.

Other functions mentioned in the options involve separate sensors or systems. For instance, measuring tire pressure and coolant temperature requires different sensors designed specifically for those tasks, and detecting fuel contamination involves diagnostics that are not performed by the O2 sensor. Thus, the primary role of the O2 sensor is indeed to measure the oxygen content in exhaust gases, which is integral to maintaining optimal engine performance