Oxygen Sensor, Remove and Install
The oxygen sensor may only be carefully unscrewed from the exhaust manifold with the engine at operating temperature.
When re-installing the oxygen sensor, its thread must be coated with special grease (black) - new oxygen sensors are pre-treated.
Remove, Disconnect
Disconnect wiring harness plug for oxygen sensor from transmission/cylinder block bracket. Unscrew oxygen sensor (arrow) from exhaust manifold.
Install, Connect
Screw oxygen sensor (arrow) into exhaust manifold.
Tighten (Torque)
Oxygen sensor in exhaust manifold - 30 Nm / 22 lbf. ft.
Connect wiring harness plug for oxygen sensor.
Remove, Disconnect 
Install, Connect 
Tighten (Torque) 