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Where is the O2 sensor located?

I’ve noticed reduced fuel efficiency and my Check Engine Light is on. I think it’s an O2 sensor problem. Where is the O2 sensor located?

avatar
Bonnie Stinson · Updated on
Reviewed by Shannon Martin, Licensed Insurance Agent.
Sorry to hear about your car troubles! The O2 sensor is normally located on the exhaust manifold near the catalytic converter.
In
newer cars
, there are usually two oxygen sensors for each catalytic converter (one before and one after). Older cars typically have a single oxygen sensor. Some modern vehicles have even more sensors!
The sensor before the catalytic converter is called the Upstream Oxygen Sensor or Sensor 1. You can find it close to the engine under the hood.
The second sensor is called the Downstream Oxygen Sensor or Sensor 2, and it is usually located close to the muffler beneath the vehicle.
If you’re looking for the O2 sensor so you can replace it, be careful not to get any oil or grease on the sensor. This is not the type of part you can usually repair, so go ahead and replace the sensor entirely—or get a skilled mechanic to do it. The part itself should cost less than $100.
Good luck!
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