Where is the O2 sensor located?
Auto repair

Where is the O2 sensor located?

08.11.2022 /

Oxygen Sensors Oxygen sensors will always be located in the exhaust system. Their function is to determine how much oxygen is left in the exhaust gases coming out of the engine and communicate this information to the car's engine...

Oxygen Sensors Oxygen sensors will always be located in the exhaust system. Their function is to determine how much oxygen is left in the exhaust gases leaving the engine and report this information to the car's engine management computer.

This information is then used to accurately deliver fuel to the engine under various driving conditions. Your vehicle's main computer, the powertrain control module, monitors the operation of the O2 sensors. If a problem is detected, the Check Engine light will come on and a DTC will be stored in the PCM memory to assist the technician in the diagnostic process.

A couple of helpful tips to help you find your O2 sensors:

  • Vehicles manufactured after 1996 will have at least two oxygen sensors.
  • 4-cylinder engines will have two oxygen sensors
  • V-6 and V-8 engines usually have 3 or 4 oxygen sensors.
  • 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 ones will be located under the car, right after the catalytic converter.

The sensor(s) located near the engine is sometimes referred to as the "pre-catalyst" because it is located before the catalytic converter. This O2 sensor provides information about the oxygen content of the exhaust gases before they are processed by the catalytic converter. The O2 sensor located after the catalytic converter is called "after the catalytic converter" and provides data on the oxygen content after the exhaust gases have been treated by the catalytic converter.

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

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