ECT Sensor No. 2

WARNING: This page is about a different car, the 2017 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.

Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION .)
Lift up the vehicle.
Remove the front under cover No. 1. (See FRONT UNDER COVER No. 1 REMOVAL/INSTALLATION .)
Drain the engine coolant. (See ENGINE COOLANT REPLACEMENT .)
Disconnect the ECT sensor No. 2 connector.
Remove the ECT sensor No. 2 using the SST.

Fig 1: Disconnecting ECT Sensor No. 2 Connector
Courtesy of MAZDA MOTORS CORP.
Install in the reverse order of removal.
Refill the engine coolant. (See ENGINE COOLANT REPLACEMENT .)