>> A << Engine Coolant Temperature Sensor Installation

WARNING: This page is about a different car, the 2008 Mitsubishi Lancer. However, it is still accessible from the selected car via links, so may be relevant.

Apply sealant to the engine coolant temperature sensor thread.
Specified sealant: Three bond 1324N or equivalent

Fig 1: Applying Sealant To Engine Coolant Temperature Sensor
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
Use special tool MB992042 to tighten the engine coolant temperature sensor to the specified torque.
Tightening torque: 30 ± 9 N.m (22 ± 7 ft-lb)

Fig 2: Identifying Special Tool MB992042 And Engine Coolant Temperature Sensor
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.