What is an Oxygen Sensors?
Also Known as : O2 Sensor, Ox sensor, Oxygen sensor
Purpose : Measures Oxygen content in exhaust stream.
In today’s modern engines the fuel delivery system has changed dramatically since the early days of carburetors. On a carburated engine the amount fuel that is delivered to the combustion chamber was controlled by a jet size and the throttle plate size and position. Although, this method is fairly simple, it is not very precise and often delivered too much fuel causing a rich condition or too little fuel causing a lean condition to the engine.
Fuel injected engines control the amount of fuel delivered for combustion precisely by increasing or decreasing the time a fuel injector is active. This time is controlled by the engine computer ECM and the sensors that send information to it. One of the key sensors is the O2 or Oxygen sensor which is made of a bi-metal ceramic element that reacts to the amount of oxygen, or lack of it, in the exhaust system.
An O2 sensor indicating a lean condition would show that there was excess oxygen remaining in the exhaust after the burn and signal the computer that more fuel was needed to maximizes the remaining air available during combustion.
An O2 sensor rich condition indicates that all the oxygen was used during the burn cycle and that unburned fuel was found in the exhaust because of a lack of oxygen. Unburned fuel i.e. hydrocarbons are a strong pollutant and a wasteful use of expensive gasoline.
The engine computer (ECM) monitors these oxygen sensors and controls the fuel delivery via the fuel injectors. If there is too much fuel remaining in the exhaust system the computer will shorten the length of time the injectors are on. When there is too little fuel remaining in the exhaust system the ECM will increase the time the injectors are on allowing more fuel.
There are often multiple O2 sensors on a engine so that the computer can measure remaining fuel thought out the exhaust. the hot exhaust will continue to burn remaining fuel provided oxygen is present. a few common locations for O2 sensors are in the exhaust manifold know as up stream because they are before the catalytic converter and down stream after the catalytic converter in the exhaust pipe.
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