I just replaced my o2 sensor on my '95 2WD 22RE and I used the OE Toyota part. If you search o2 sensor on this forum you'll find a list of suppliers and I picked the first one. The parts diagram only shows one sensor (maybe I was looking in the wrong area) but that's the important one. If you look under the driver's side, behind the front wheel, on top of the exhaust you'll see the sensor- it took me all of 15 minutes to change.

 

I have a 94 2wd with 4-cyl 22RE. I replaced both sensors (pre-cat and post-cat) after I failed CA smog last year (185000 miles). it was a slam dunk. breaking the bolts loose took longer than anything else. disconnect battery, unplug sensor (has about 3-4" of wire. plug is close to sensor), remove 2 bolts, bolt new one on, plug, battery, DONE. mine were extremely corroded, along with the cat. I think when one goes, the other(s) go(es) too if you don't replace right away. I don't think I even jacked my truck up.

** you know what I can't remember if I have 1 sensor or 2. I did the same for my wife's explorer at the same time, so I might be confusing the 2 vehicles. check your manual. **

 

Thanks for the replies.
I noticed that there is a huge difference in price between the OEM units and the 'universal' ones, and that at least in the online pictures the OEM units have a sort of flange with two bolt holes that the sensor is mounted into and the universals don't have that. Can the original sensor be unscrewed from the flange and the original flange reused? Or am I better off biting the bullet and shelling out for an OEM unit...?

 

the flange was seperate one mine. although for the best seal a new one is preferable. I don't know maybe I got OEM parts thru AutoZone, because I didnt have to splice any wires, they came with flange and electronic clip unit. if you re-use flange make sure both surfaces are flush.

 

Here's a previous thread on O2 sensors.

www.sparkplugs.com has some pretty affordable O2 sensors that are plug and play. Not much different from universal ones so I'll shell out the cash for the plug and play ones.

 

usually a bad O2 sensor will result in a richer mixture and better performance. In fact it is not uncommon to have a customer remark that their vehicle does not run as well since the O2 sensor was replaced.

Sometimes though, the voltage from the heater circuit will short to the sensor circuit and drive the mixture lean. This can be tested for and I would suggest to do the diagnosis before throwing parts at it.