Step 1: Materials
1. A 05 Saturn VUE
2. O2 sensor AC Delco Part # 1255-8143 (I got mine from Ebay for $50 new)
3. O2 sensor socket. ($10 from Advanced Auto Parts)
4. 3/8 drive ratchet.
5. 10 min of your time.
(Note: In the picture I am showing the old O2 sensor that came out of the vehicle. I had already replaced it just prior to doing this instructable.)
Step 2: Locate the O2 sensor
Please make sure that the engine is cooled down. We don't want any burns due to this instructable.
Locate the faulty O2 sensor. I have marked on the picture where to look. It is located on the back side of the engine between the exhaust manifold and catalytic converter. ( I would also like to add: This is Bank 1 Sensor 1. If you had a computer scan that said O2 sensor Bank 1 Sensor 2 was bad then you will need to replace the O2 sensor just behind the catalytic converter. )
Step 3: Remove the bad sensor
After you have the plug loose from the vehicle. You will need to use the O2 sensor socket and ratchet to remove it from the exhaust manifold. Set the ratchet to turn counterclockwise. Place onto the sensor and start turning. It will likely take some effort to remove so don't hesitate to use some force.
Step 4: Install the new one
NOTE: If you do happen to have a check engine light on. Go have the light reset. It may be in memory from the previously bad O2 sensor and will need to be reset. If it comes back on again, then you should have a tech look at your car. Something else may be going on.