I took my car in friday to dealer & they said one of my Oxygen Sensor's are bad & replaced it under warranty...forgot to ask him WTF is an oxygen sensor.

Sorry I'm not totally mechanically inclined & dont know what this is...can anybody tell me?

p.s. i did a search on what is oxygen sensor but too many threads came up & none answered the question

 

It looks almost like size of a spark plug.. There one in the y-pipe. You can 2 front bank 02's and 2 rear O2's if your a cali spec.

 

The o2 sensor detects the amount of oxygen in the exhaust...before and after the cat for those who have 1996+. The ECU will make changes based on the signals that the o2 sensor sends to it.

 

A pollution control device which measures the amount of oxygen in the exhaust stream and sends that information the ECM. It controls the fuel-air mixture entering the engine. Also called a lambda sensor, exhaust oxygen sensor, or an O2 sensor

 

Thanks everyone for the knowlegde lesson
dave thanks for the pic