2001 chevy tahoe oxygen sensor? check engine light?

[Pete]

i have a 2001 chevy tahoe and my check engine light came on, i got a diagnostics and its says my o2 sensor is not working. (bank 1, sensor 1). well my truck has 4 o2 sensors and i wana know which one is Bank 1, sensor 1? is it on the drivers side or passenger side?

 

[fatboy61717]

All i know is bank 1 is before your cat.

 

[thecman26]

Just go ahead and save yourself the trouble and replace both pre cat sensors and you should be good to go! If you only do one, then Murphy and his awful laws will jump oyu and the other one will go out shortly thereafter. Kinda like if one headlight goes out replace them both... Same rationale behind the thinking there!