An oxygen sensor plays an important role in the efficient operation of an automobile engine. While a car will run without an oxygen sensor, driving without one is not a good idea for a number of reasons.
The oxygen sensor measures the amount of oxygen in the exhaust gases. With this information, the engine's computer adjusts the mixture of fuel and air used for combustion. Without information from the oxygen sensor, the engine will often run rich -- too much fuel in the mixture, resulting in an increase in fuel consumption.
The rich fuel mixture will result in the engine running at a hotter temperature than is needed which may result in detonation, often referred to as spark plug knock. Detonation is caused by fuel burning in the cylinders from heat and not the ignition's spark. This early combustion and the hotter temperatures will increase wear on the valves, pistons and other engine components.
The hotter engine temperatures will be transferred to the exhaust system. Catalytic converters, which are very expensive to replace, may be damaged by the increased heat. The rich fuel mixture will result in unburned gas in the exhaust which will also accelerate exhaust component deterioration.
