Good afternoon everyone.
2004 Camry v6 , check engine light is on which indicates P2238, air fuel sensor, bank 1 , sensor 1.
Where's this sensor located? Is it upstream or downstream? Part number will be much appreciated.
Thanks,

 

Bank 1; is the cylinder head closest to the firewall.

Sensor 1; is the first sensor on the exhaust system for a cylinder bank.

The first sensor on the exhaust for the cylinder head closet to the firewall. The sensor is in front of the converter.