Welcome to brain Stuff from how stuff Works dot com where smart Happens. Hi Am Marshall Brain with today's question, how does the oxygen sensor in a car work? Every new car and most cars produced after, have an oxygen sensor. The sensor is part of the emissions control system and it feeds data to the engine management computer. The goal of the sensor is to help the engine run as efficiently as possible, and also to produces few emissions as possible.
A gasoline engine burns gasoline in the presence of oxygen. It turns out that there's a particular ratio of air and gasoline that's perfect, and that ratio is fourteen point seven to one. If there is less air than this perfect ratio, then there's gonna be fuel left over after combustion. This is called a rich mixture. Rich mixtures are bad because the unburned fuel creates pollution. If there's more air than this perfect ratio, then there's excess oxygen. This is
called a lean mixture. A lean mixture tends to produce more nitrogen oxide pollutants, and in some cases it can cause poor performance or even engine damage. The oxygen sensor is positioned in the exhaust pipe and can detect rich and lean mixtures. The mechanism in most sensors involves a chemical reaction that generates a voltage. The engine's computer looks at the voltage to decide if the mixture is rich or lean, and it adjusts the amount of fuel entering
the engine accordingly. The reason why the engine needs the oxygen sensor is because the amount of oxygen that the engine can pull in from the outside air depends on all sorts of things like the altitude, the temperature of the air, the temperature of the engine, the barometric pressure,
the load on the engine, et cetera. When the oxygen sensor fails, the computer can no longer sense that air fuel ratio, so it ends up guessing and your car performs poorly or uses more fuel than it needs to be sure to check out our new video podcast, Stuff from the Future. Join how Stuff Work staff as we explore the most promising and perplexing possibilities of tomorrow. The House Stuff Works iPhone app has arrived down at it today on iTunes,