Air Fuel Ratio Sensor 1, Heated Oxygen Sensor 2

WARNING: This page is about a different car, the 2013 Infiniti FX50. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION:

Before installing a new sensors, clean exhaust system threads using oxygen sensor thread cleaner (commercial service tool: J-43897-18 or J-43897-12), and apply anti-seize lubricant (commercial service tool).
Sensors are not reusable. Replace them with a new one after removal. When replacing them, handle with care not to impact on them.
When installing the new sensors, set the heated oxygen sensor wrench [SST: KV10114400 (J-38365)] (A) in the hexagonal part to tighten the them.
Prevent rust preventatives from coating the sensor body.

Fig 1: Removing Heated Oxygen Sensor 2 Using Heated Oxygen Sensor Wrench
Courtesy of NISSAN NORTH AMERICA, INC.
Never over torque sensors. Doing so may cause damage to the sensors, resulting in "MIL" coming on.