Have these codes on my 2002 suburban. Not sure where they are located. I think the P0131 is an o2 sensor. Not sure about the code P0161 or where it is. Any help would be greatly appreciated. Thanks

 

131 is upstream (left side) O2 sensor low voltage
161 is downstream O2 sensor right side heater performance.

 

Thanks for your quick reply. Does upstream mean the one closest to the header? I bought both sensors from Auto-Zone. The P0161 has a different connector than the other 4 ho2 sensors. Does that mean they sold me the wrong one? Thanks again for any help.

 

Yes it does