Bank 1, Sensor 1 Left-Bank Pre-catalytic Oxygen (O2) Sensor

(1) After dropping the engine under cover, I unhooked electrical connector of the pre-catalytic (bank 1, sensor 1) oxygen sensor.

(2) Access to the oxygen sensor for removal is a bit tight but doable.

(3) A nearby metal heatshield prevented my use of my standard 22mm oxygen sensor socket

However, I was able to use my 22mm crowfoot wrench socket with extension to break it loose (see inset).

I spread some anti-seize compound included with the new oxygen sensor in the Denso box (pictured earlier), tightened it down with my 22mm crowfoot wrench, and reconnected the electrical connector of the new oxygen sensor.