Here's a little back story on the car. When I got the car I did a clutch job on the car. When putting the trans back in I accidentally pinched the wires for trans speed, coolant temp, and 2nd o2 sensor.
I spliced everything back together and things seemed to be working fine. But months later my tuner told me the previous guy had the 2nd o2 sensor codes turned off. So we turned them back on. Initially the 02 wasnt even working at all. So I changed the 02 with an oe replacement. Now the o2 would show codes of heater circuit insufficient activity , before replacing it was the sensor itself had insufficient activity.
So I checked all my wiring to the sensor to make sure nothing was grounded and all my wires were hooked up right, as in I spliced them back together correctly. Everything checked out. When running a diag tool, it showed the secondary o2 heater circuit had no voltage across whatsoever. I will link some pics. This is what leads me to believing that I burnt out the pin for the heater circuit on the pcm. Is there anything else I should test first or try? Thanks for any info...
2009 cobalt ss sedan f35

 

does it have a cat on it? unless ur in an emissions inspection state, i recommend turning the codes off again, removing the o2 and be done with it. if u have a cat then i guess dont do that lol. find a pin out for the ecu and probe the individual wires for continuity. at the ecu plug and the o2 plug. then check them all for short to ground and power, if all checks out. u will need to check alldata for the resistance the wire should be when plugged into the ecu and key in run position but not running. if its not the correct resistance, ur ecu circuit is shot and u need a new ecu. also check fuse to make sure its not blown. i think its the exhst fuse. something like that

 

Exhaust pipe leakage. Check pipes
out!

 

08 Chevy Cobalt SS. I have an issue with my rear o2 sensor heater circuit. I just got a ZZP high flow cat(hp tuned for it off course). My problem is p0037 which puts me in closed loop fault giving me terrible gas mileage all while taking the edge off performance. Now, I know it's been said to disable the codes in hp tuners and be done with it. The problem with that is all my down pipe codes are disabled & they still pop up causing the dreaded closed loop fault. Welp, come to find out that if you down load the new hp tuners drivers & updates,you can no longer edit codes that effect emmissions. They are in a greyed out box you cannot edit. If you have an older HP tune & never downloaded the new updates you should be unaffected. My solution was to fix the problem by buying a new sensor. It seems HPT has surrendered to the EPA

 

Yes they have locked codes in HPT. You can do a course which doesn't take super long and after it will unlock everything you need.