What Is Bank1 And Bank2

[wishful1]

I have a 96 LS400 and I'm getting code PO420 Bank1 and PO430 Bank2 Catalyst Efficiently below threshold. Can anyone tell me which 02 sensor these are. I know there are 2 in the front and 2 in the back, but I need to know what Bank1 and Bank2 means.

Thanks for any help.

[sha4000]

I have a 96 LS400 and I'm getting code PO420 Bank1 and PO430 Bank2 Catalyst Efficiently below threshold.  Can anyone tell me which 02 sensor these are.  I know there are 2 in the front and 2 in the back, but I need to know what Bank1 and Bank2 means.

Thanks for any help.

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you have to find out which side of the engine your #1 cylinder is on and that would be bank 1 and of course the other side is bank 2 but are you sure those are 02 codes it sounds like your cats might be going bad(lets hope thats not the case)

[pachocco1]

This may help.

insp.pdf

comp.pdf

[pachocco1]

This too.

cip0420p.pdf