Where Is the O2 Sensor Located?

Oxygen sensors O2 sensors will always be located in the exhaust system. Their function is to sense how much oxygen remains in the exhaust that is flowing out of the engine, and report that information to the vehicle’s engine control computer.

A couple helpful tips to assist in locating O2 sensors:

Vehicles built after 1996 will have at least two O2 sensors
4 cylinder engines will have two oxygen sensors
V-6 and V-8 engines will usually have 3 or 4 oxygen sensors
The sensors will have 1-4 wires on them
The front sensor(s) will be located under the hood, on the exhaust, very close to the engine
The rear one(s) will be located under the vehicle, directly after the catalytic convertor
The sensor(s) close to the engine are sometimes called “pre-cat”, being located before the catalytic convertor. This O2 sensor provides information about oxygen content in the exhaust before it is treated by the catalytic convertor. The O2 sensor located after the catalytic convertor is referred to as “post-cat” and provides data about oxygen content after the exhaust has been treated by the catalytic convertor.

When replacing O2 sensors that have been diagnosed as faulty, it is strongly recommended to obtain original equipment brand sensors. They are designed and calibrated to work with your vehicle’s computer. If you have a V6 or V8 engine, replace sensors on both sides at the same time for best results.