which o2 sensor

[audiophile]

do you guys know which o2 sensor needs replacing the one before or after the cat? which one have you guys done?

[KenzBenz]

i've replaced the one after...what did the scanner report?

[Eurosport]

same here i did the one after the cat

[audiophile]

if i remember, i think it said the one after

[moebiusgold]

I relplaced both even though I had no codes. The front one monitors the combustion mixture and the rear one monitors the health of the cat converter. My rear one looked brand new but the front one was totally covered with white powder.

[audiophile]

so which one do you think i should change?

[max2105]

It is a good idea to replace O2 sensors at 100K mile intervals. Bosch recommends so.
I had replaced both of mine only a few short weeks before my car was totaled. Total cost:$210.

[moebiusgold]

Wow, you got the best price for 2 sensors installed that I have ever heard of.

[max2105]

The price was for parts only. I installed them myself (and now removed them and up for sale).