Need some help with O2 sensors

[buckshot85]

On a NNBS, In this case a 2009 gmc where do I need to mount the 02 sensors after installing highflow cats? Is it like on F150 and just mount them after the cats? I was told by one guy mount a set in front and one behind the cats, I thought there were only two 02 sensors though? Some help would be greatly appreciated fellas

 

[Kennyray]

On a NNBS, In this case a 2009 gmc where do I need to mount the 02 sensors after installing highflow cats? Is it like on F150 and just mount them after the cats? I was told by one guy mount a set in front and one behind the cats, I thought there were only two 02 sensors though? Some help would be greatly appreciated fellas

Where are your sensors located now? On my Ford I have 1 before and one after on each side. I'm sure your GMC is the same way.

 

[Draenor]

You should have two pre-cat and two post cat. One set per bank.

 

[buckshot85]

Correct I have two before and two after my cats. Guess I was just worried they needed to be after the cats. I was told to reinstall them as they are now and should have no problems

 

[Kennyray]

That is correct...