Can someone tell me where how many fuses there are to the 02 sensor? Is there a fuse under the hood somewhere other than the I/P panel on the driver end of the dash? Also, is there a relay associated with the 02 sensors, if so where is it? 1996 S10 Blazer 4.3 2wd

 

Your truck has four O2 sensors total. There is one on either side close to each exhaust manifold on the y-pipe. These two are the upstream (B1S1 & B2S1) sensors. There will be one directly ahead of the catalytic converter and another directly behind the catalytic converter. These two are the downstream (B1S2 & B1S3) sensors. Here is a view showing their locations:


I believe that the heaters in each O2 sensor are powered by the ENG fuse which also powers some of the circuits in the PCM amongst a lot of other things. There are no relays for the O2 sensors.

Here is a fairly comprehensive wiring diagram for the engine controls:

 

Swartlkk,
I've been looking for a diagram of the locations of the O2 sensors for my 97 Blazer LE 2/dr 4.3 4x4. Is the diagram you posted {above} the same as for my 97 Blazer?
I'm getting OBD II code P0141 with my Actron pocket scanner. My understanding that code is for Sensor Heater Circuit Malfunction (Bank 1- Sensor 2) is that correct?
I have changed going by the diagram B1S3 and B2S1 so far, but with no results. After looking at the diagram it's obvious now that I changed the wrong O2 sensors, if in fact that diagram is for my Blazer! Plus the fact that the check engine light is still on!!
Thanks in advance for any help..

 

does anyone know where I can get a pic of wiring diagram for O2 sensor on a chevy Blazer 2001?

 

The ones posted in the OBD2 section (see the link in my sig for the index) will apply to your vehicle as well. Search FTW!

Closing this 14 month old thread.