Sedan (4SD)

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 .)
Partially peel back the trunk lid trim. (See TRUNK LID TRIM REMOVAL/INSTALLATION .)
Turn the socket counterclockwise and remove it in the direction of arrow (1) shown in the figure.

Fig 1: Locating License Plate Light Bulb Socket
Courtesy of MAZDA MOTORS CORP.
CAUTION:
- If there is oil or dirt on the surface of the light bulb, excessive heat will build up and the life of the light bulb will be shortened. If the light bulb glass area is touched, wipe off any dirt using a soft cloth dampened with detergent diluted in water (approx. 5%).
Remove the license plate light bulb.

Fig 2: Removing License Plate Light Bulb From Socket
Courtesy of MAZDA MOTORS CORP.
Install in the reverse order of removal.