Depending on the make, model and engine type, oxygen sensors can be located in a variety of places on your vehicle. Below are some of the more common locations.

 

Traditional V6 & V8

A traditional V6 or V8 engine typically contains a left and right bank pre-catalytic converter oxygen sensor, as well as a post-catalytic converter oxygen sensor.

 

4 Cylinder Transverse

A 4 Cylinder Transverse engine typically has a pre-catalytic converter oxygen sensor and a post-catalytic converter oxygen sensor.

 

V6 & V8 Transverse

A V6 or V8 Transverse engine typically has a front (or left) pre-catalytic converter oxygen sensor, a rear (or right) pre-catalytic converter oxygen sensor, as well as a post-catalytic converter oxygen sensor.

 

4 & 6 Cylinder In-Line

A 4 or 6 Cylinder In-Line engine typically contains a front pre-catalytic converter oxygen sensor, a rear pre-catalytic converter oxygen sensor, as well as a post-catalytic converter oxygen sensor

 

Below is a diagram outlining the typical engine bank configuration of a 6 and 8 cyclinder engine.  Notice that Bank 1, containing cylinder 1, is always the most forward cylinder on the block.