What is an oxygen sensor?

The oxygen sensor, also known as the lambda sensor, was developed in the late 1960s by Dr. Gunter Bauman for the company Robert Bosch GmbH. This sensor is an electronic device used to measure the proportional amount of oxygen in a liquid or gas. The original oxygen sensor was made from ceramic coated zirconia and platinum. In order to make the O2 sensor more capable of mass production, planar oxygen sensors have been developed. This retrofitted O2 sensor was developed by NTK in 1990 for use in the Honda Civic and Accord. Made from layers of high temperature co-fired ceramic (HTCC) green ribbons, the current style of sensor is made more efficient than the original style sensors.
What is an oxygen sensor used for in a car?
All cars manufactured after 1980 are equipped with an oxygen sensor. It is located in the emissions control system. When operating, the O2 sensor sends data to the management computer located inside the engine. In your car, a functioning O2 sensor ensures that your engine is operating at peak performance. Additionally, this sensor monitors your emissions and alerts you when emissions are too excessive. For states that have vehicle inspection programs to regulate emissions, using the CEL and O2 light will alert authorities to any excessive emissions. Therefore, if one or more of your oxygen sensors are faulty during an emissions inspection of your car, you will likely not pass the inspection.

What are oxygen sensors used for?
When a gasoline engine burns gasoline, oxygen is present. Oxygen in an engine is the result of a number of factors, including air temperature, altitude, engine temperature, load on the engine, and barometric pressure. The ideal ratio for oxygen and gasoline is 14.7:1, which varies slightly for different gas types. In case there is less oxygen, the fuel will remain after combustion, which is called a rich mixture. On the other hand, if there is more oxygen present, it is called a lean mixture. Both rich and lean mixtures are bad for your car as well as the environment. A rich mixture results in fuel that does not burn and creates pollution. A lean mixture generates nitrogen oxide pollutants, which can lead to reduced vehicle performance and engine damage. Oxygen sensors are positioned near points in the exhaust system to determine if there are rich or lean mixtures in your car.
Typically, an O2 sensor creates voltage due to a chemical reaction resulting from an unbalanced gasoline-to-oxygen ratio. Most car engines can determine how much fuel to consume in the engine based on the O2 sensor voltage. If your oxygen sensor is not working properly, your engine management computer cannot determine the air/fuel ratio. As a result, the engine is forced to guess how much gasoline to use, resulting in a dirty engine and a poorly functioning vehicle.

How to Test an Oxygen Sensor
To test your oxygen sensor, you can either leave it attached to your vehicle or remove it for testing. Testing requires two tools: a high impedance digital voltmeter and a back probe. A mechanic at a Meineke repair shop has these necessary and specialized tools to check O2 sensors. The first step in checking an O2 sensor is to locate the surrounding wires to ensure they are intact and without visible signs of wear. Next, the vehicle must be started and allowed to run until the engine reaches 600 degrees F to ensure an accurate sensor reading. Using the rear probe and voltmeter, the oxygen sensor is measured at a set number of points and under specific conditions to determine any faulty readings. Since testing an oxygen sensor requires specialized training and tools, it is best to let a mechanic perform this voltage-based test.
for more information:
https://resource-center.meineke.com/oxygen-sensor/
https://www.tirekingdom.com/info/a20086/what-is-the-o2-sensor-
https://shop.advanceautoparts.com/r/advice/cars-101/what-is-an-o2-sensor

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