I have a 2001 Blazer ZR2. I got the check engine light code read and I need to replace the oxygen sensor from Bank 1, Sensor 2. So which one is that? The Advanced Auto parts guy didn't know, and in fact according to their computer I should have 4 O2 sensors and told them I only found 3. I just need to know which one it is, I am thinking the one by the C.Converter, but not sure.

 

P0137? Should be the post cat converter.

 

It is the post-cat sensor.

Before you replace an emissions monitoring sensor, clear the code and see if it comes back.

What was the code? Diagnose the problem before spending money.

 

+1, the cat may be bad. If the cat is bad you should figure out what killed it. Have you noticed a drop in power and mpg?

 

I haven't noticed any loss of power and I don't know specifically what the code was that they read. I did clear the code out and the light comes back on each time after driving for 10-15 miles.

I will probably just replace the sensor after the converter, clear it and see what happens.