Post-cat O2 sensor - OBD1.5

[xtremerevolution]

While I was under my car today I noticed that I have a post-cat O2 sensor, something I thought only OBD2 cars had.

 

I also know that its the original O2 sensor from the factory, since I've never cared to notice it before.

 

Anyone know what this thing does or is supposed to do? Is it only there to tell you if your cat is functioning properly, or is there more to it?

 

I'm trying to decide if I should replace it or not, since it has 213k miles on it.

[RobertISaar]

serves the same purpose as it would on OBD2 cars: monitoring the cat efficiency. there are trouble codes for it... as long as they aren't getting triggered, i'd leave it, it doesn't affect fueling in any way.

[xtremerevolution]

serves the same purpose as it would on OBD2 cars: monitoring the cat efficiency. there are trouble codes for it... as long as they aren't getting triggered, i'd leave it, it doesn't affect fueling in any way.

 

Sweet!!! 213k mile O2 sensor FTW!

[BXX]

Yea, downstream O2s dont normally fail or get lazy.. They dont do much as even the voltage output from them is pretty constant.

 

And midget man is correct, its a sensor that pretty much tells you if your converter is working right. Although often a cat efficiency code can be triggered with some other underlying cause (i.e. misfire or a right/lean condition that a lazy upstream didnt catch)