OBD II reading for Emissions problem bay 1 ???

I have a 1996 Blazer (W code). Occasionally (usually when I drive a long distance at 60mph or more) my Check Engine Light comes on. I had autozone run the OBD II test to get the reading "low emissions, bay 1" . They reset it and it comes back every once in a while with the same error. Can anyone tell me what bay 1 might mean? I thought it may be the 1st Oxygen sensor of the many that are on this thing. I heard GM can do a better test than Autozone but its 80 bucks too. Usually I just remove the two 20amp fuses to the guages for a minute or two to reset this myself now instead of having Autozone do it. I dont want to guess at which oxygen sensor it may be (if it is that) since each is about 50 bucks. Can anyone give me some info??? :banghead:

Are you sure it wasn't TWC low efficiency bank 1, if so it might mean you need a new catalytic

do you have a number for the code??? if it comes back get the code number.

try cleaning your O2 sensors with a o2 safe injector cleaner or something. i cant remember the code i got but it ended up being the 1st O2 sensor. It was way darker the the 2nd.

I will get the code, I cannot remember the number it gave me. I did put a new cat on around a year and a half ago. I did have some issues with the weld on it but fixed that one.