Is it normal for the after cat O2 sensors not to read on scan of live data on a ‘97 Z28/LT1?

 

The only OBD-2 data logs I've looked at recently are those produced by GaryDoug's OBD-2 scan/data logging program, They do not show the after-cat O2 sensor readings. I suspect they are not available in the "basic" GM OBD-2 data, which conforms to Federal OBD-2 requirements, but may show up in a scan made with a device licensed by GM to read "GM Enhanced Parameters". The license to read and display GM's proprietary data reportedly costs $50,000.

What are your concerns regarding the after-cat O2 sensors?

 

I was just wondering if it was normal for them to not show.

I have another question. My Z28 has fairly high NOS emission, over 500 sometimes which causes it to fail. Is that normal?

 

High NOx is generally the result of 1) engine running hot, 2) engine running lean, or 3) faulty EGR system. If you're not passing emissions due to NOx, there's a problem.