Is the O2 sensor the same before and after the cat convertor?
I only found 2 part#s for the O2 sensor, a "Right" and a "Left" 25312196 and 25312197 but it did not specify before or after the cat for a '99 LS1 TA.

 

IIRC, they are the same.

 

It is probably the same sensor, but it may have a different length of wire and/or connector.

-Geoff

 

You are correct.

 

If that's the case, how do I order all 4 if there is only a "right" and "left" part number??
There's an O2 before and after each cat and if you are saying they are the same sensor for both the before and after sensor on the same side but diffent wire legths and connector why is there not a front and back part # also??

I think you are referring to if the left and right sides are the same which is not what I'm asking.

 

No the left and right have different length wires. All 4 sensors are the same in size and operation and have the same connector. The length of the wires vary.
Go to a GM dealer parts counter and have the parts person pull up the part numbers for you.

 

Yes, I know the left and right would be different wire lengths, hence the different part number. Are the front and back on the SAME side the same part number as well is what I'm trying to figure out.

 

I don't know, that's why I suggested stopping into any GM dealer. The parts guy can tell you in just a few minutes.