Oxygen sensors or lambda probes are sensors that are located in the exhaust manifolds, their function is to measure the concentration of oxygen in the exhaust pipe and inform the injection module if the air/fuel mixture is rich or lean.
This component has undergone great evolution in recent years and has become increasingly specific for each vehicle application. Its number of wires may vary for older vehicles and newer ones have 4 wires with fast heating.
As for the location, they can be pre-catalyst or post-catalyst.
Linear or wideband sensors:
They are highly accurate oxygen sensors that indicate the lambda of the mixture, that is, they inform the injection module precisely how the air/fuel mixture is. This information allows the injection system to work with different lambda strategies and reduce consumption and pollutant gas emissions. This type of probe requires a controller chip that is normally installed inside the injection module.
They are also widely used in programmable injection systems and racing applications, as they allow the preparer to precisely adjust the air/fuel mixture.
Usually its use is as a pre-catalyst probe, the post-catalyst probe is usually of the binary or conventional type.