An oxygen sensor works like a generator and contains a bulb, which is coated in platinum and contains two strips of platinum that serve as electrodes. The oxygen sensor is placed in the exhaust manifold and is responsible for monitoring how much unburned oxygen is in the exhaust as it leaves the engine. Measuring the oxygen levels in the exhaust allows the fuel mixture to be properly gauged, which allows the user to see if the system is burning lean, which means that it is burning more oxygen, or if it is burning rich, which means that it is burning less oxygen.
There are multiple factors than can affect the oxygen levels in the exhaust, results in either burning lean or burning rich. These factors can include air temperature, engine coolant temperature, barometric pressure, throttle position, air flow and engine load. Issues with the oxygen sensor can affect numerous processes in the vehicle. Oxygen sensors are quite durable, especially considering the environment in which they work, but they can wear out after some time and require replacement. It is important to keep the oxygen sensor working, because it works to gauge the fuel mixture. An unbalanced fuel mixture can lead to greater emissions, which can lead to further issues with the exhaust system in the vehicle.