UPDATE:
Still having secondary air flow codes, sometime but not always o2 heater resistance. This is even after replacing check valve.
This morning I had secondary air flow, with a pending stuck valve.
Something else, if the light is going to come on it only happens after it is started. This make sense since that is when the secondary air flow is tested. Also seems to be since we have had some warmer weather it happens more often almost daily, when we had freezing to sub freezing it might happen once in 10 or so days.


I have the android app for obdll access. One of the functions is labeled test, but it shows mode 6 data.
Anyone familiar with "mode 6"? (maybe a thread by itself)
Sometime when I check it these item fail other time they pass.
Here is a snipit.
----
TID:$05 CID:$05
- Rich to Lean sensor switch time(calculated)
Test incomplete or dependant test failed
--
TID:$05 CID:$06
- Rich to Lean sensor switch time(calculated)
Test incomplete or dependant test failed
--
TID:$05 CID:$07
- Rich to Lean sensor switch time(calculated)
Test incomplete or dependant test failed
--
TID:$05 CID:$08
- Rich to Lean sensor switch time(calculated)
Test incomplete or dependant test failed


It was suggested to check the grounds.
All the grounds seem tight, just looking for random ones. I did focus on the area of the secondary air flow and o2 sensors. Any particular ground for me to check?

My gm friend brought home his computer that can command the systems. First not running he turned on the blower, and then the valve. Look for air flow at the exhaust, then started it and watch the o2 sensor as we switched it on and off, all worked as expected. His thought it's something is flaky and when it fails then we know :-)


It not causing any driving issues, other than the light disable the remote start. So I keep clearing it.


I starting to wonder if it is the o2 sensors. Sometime the message, it's stuck open other times it's incorrect air flow. Once or twice out of fifty times, I got a o2 heater resistance with the incorrect air flow.
Bad 02 sensors? Any way to test and be sure?