I just went through this myself on my 97 ford Explorer, V8, 5.0ltr. Here are some things to keep in mind:
The upstream sensors are green. The downstream sensors are blue. (There are two each on my truck)
If you slide under your truck from the passenger side, (your head is toward the drivers side and your feet are hanging out the passenger side), you'll be looking at your exhaust and following it from the front of your truck to the back. Not far from the front you'll come across a six sided shape with exhaust pipe going in and out of.
There will be an O2 sensor on the left of the six sided part. (that is bank 1, sensor 1 upstream) On the right side you'll find another one, (bank 1 sensor 2 downstream). A little further right is another O2 sensor, (bank 2 sensor 2 downstream).
You'll need a 7/8 wrench. The O2 sensor at the furthest right will require a flared wrench, since its in such a tight spot.
To get to the clips, the easiest way is to remove the center console between the drivers seat and passengers seat. Its relatively easy. (I just did this yesterday) Pull out the little shelves (I don't have an ashtray). They yank out fairly easy. Look at the base and you'll see four little bolts. Remove those. Hopefully you are stronger than me for this next part. Get into the backseat and pull back on the console. And I mean give a good grunt pull. Keep trying, it'll come off. You may have to trim your carpet to get to the next part. I used a box cutter and trimmed a little bit to the top of the hump, that way when you put the console back on, you won't be able to see the cut in the carpet. Under the carpet you'll find a metal plate with four bolts. Remove the bolts, pick up the plate and 'viola' there are the clips for the O2 sensor. (If you have very skinny arms, you might be able to get to the clips from underneath the truck, but its doubtful.)
You now have access to 3 of the 4 O2 sensors.
For the 4th O2 sensor (bank 2, sensor 1 upstream), go under your truck from the drivers side. Follow the exhaust from the front to the back. Its not far from the front. Its pretty easy to see. Near the fuel filter, but the O2 sensor hangs pretty low. You'll see the wire ballast. This one is the easiest one to replace. Just need a 7/8 wrench.
Hope this helps.
Btw: I'm a 50 yr old woman, 5'2, 150lbs with a disability. If I can do it; Anyone can do it!
All of the information above can be found on this site. This site is where I found all of it.
I was so excited yesterday when I got the center console off and found the O2 sensor clips! I was like, "I'm the man!" "I'm so awesome!!" "I did it!!" I was so pumped. But the real credit goes to the people on this site.
Thanks everyone!! And feel free to correct or clarify my post.
Faith
