There are 4 oxygen sensors on this car.
2 are upstream called sensor's #1 (in between the engine and the catalytic converter) and 2 are downstream called sensor #2 (after catalytic converter before the muffler).
Bank #1 is the side with cylinder #1 which is the the side closest to the passenger compartment and Bank #2 is the opposite side of the engine nearest the hood release.
Both oxygen sensors you need are the same part # about $50 each. Bank #1down; Bank #2down.
Step #1) use 2 ramps not a 1 floor jack to prop one side up. You will not fit under the car all the way without them.
Step #2) You will need to soak the old sensors with WD40 a couple times for no less than 20 minutes then turn the car on and let the pipes heat up real good. This heats up the rusty metal allowing the threads to expand on the pipe, while the sensor's threads usually maintain their size thus allow you to loosen the sensor with a hole-lotta elbow grease.
Step #3) After you crack them loose you can then disconnect the wiring harness. Good luck though, they are hard to reach and took me a really really long time to disconnect. I only had a long screwdriver and it took me like an hour. After that you can unscrew the sensor and replace them. Plugging it back into the harness only took me a couple minutes.
To turn off the Check Engine Light either wait a couple days before it clears or disconnect the battery for a good 10 minutes.
Good luck.
