Looking for instructions on how to replace an oxygen sensor on my 2002 Monte Carlo... Bank 1 Sensor 1

 

Unplug the old sensor, unscrew the old sensor with an O2 wrench (has opening for the wire to pass through), add some antiseize to the new O2 threads (if not applied from the factory - make sure not to get it in/on the sensor head), screw back in with your O2 wrench, plug electrical connection back in.

 

I recommend spraying WD-40 or Rust Buster around the threads at least the day before removing it. Also, use a quality O2 sensor socket - the cheap ones flex and can break, causing a more difficult job.

 

Use penetrating oil, wait 20 minutes, warm the engine for 30 seconds until you start to smell the oil burning off, then add another round of oil, wait 10 minutes, add more penetrating oil and wait 10 minutes or ideally longer. Use a oxygen sensor socket, and mine came off so easy following that. If your car has more rust, then wait until the next day, adding penetrating oil now and then while you wait.

When replacing O2 sensors best to do both at the same time. Follow the same procedure for the second O2 sensor, ideally use penetrating oil on them at the same time. BOth my sensors came off very easy, as the heating expands the metal to allow the oil to penetrate better.