Just wanted to let everyone know the difficulty I had with replacing the Drivers side top O2 sensor on my 02 sc430. It really Isn't that difficult but its a tight area to get your hand into. The sensor itself is easy. I was not able to get a ratchet on the O2 socket but was able to get a 22 mm boxed end wrench in. This worked ok for getting the sensor out. The problem was getting the connector disconnected. They have a medal cover facing away from you to keep the heat off the sensor. It;'s a great idea but as I said there isn't enough room for two hands to disconnect. What I was able to do was work one hand up to push a very small slotted screwdriver into the disconnect slot and push it in (even with my hand hurting due to lines being in the way) I finally was able to push it in far enough to with the other hand pull just the O2 sensor wire and pull it away.
Changed it out and now had to plug the connector in. I had to shine the drop light just so I could barely see the connector and reach up and push the connector together. Like I said this sounds easy but there is not much room to do this. you are working with the ends of your fingers (two) mostly to do this. It's a great sound to hear them come together. Fired it up and cleared the code.
I bought the sensor from Rockauto.com and they had better prices that NAPA. About half the cost. Made sure it was the exact replacement due too did not want to do again. I hoped this helps anyone who tries to do this them self. The rear 02 sensors are not a problem. They are in the open and should take minutes. The top drivers side took me a hour to do. I did not say any bad words. Of course the smaller hands would make this easier. Of course if the shield came off it would have helped. If anyone has done this and has an improved method let me know. Might do it again someday once my scars heal...... Ted from Seattle