Originally Posted by BlueXJ
If the computer didn't tell you then replace them all.
There is a socket with a slit in one side that is made for O2 removal. I have two, one in my Jeep Toolbox and one in my shop toolbox. Heat usually helps to keep from breaking the bung out of the exhaust pipe or header..
X2 run the car around town for a while then slap on some gloves and GET ER DONE........
If you dont know when the last time they have been changed chances are good they are original. almost everyone over looks the replacement/funtion of a o2. They have a milage life spam. Dont wait for the computer to tell you they are faulty. Most shop manuals reccomend between 50-75K replacement. If your wallet can take it do them all. Use bosch!!