Card Key Battery Replacement [Advanced Keyless System]

Pull out the auxiliary key.

Fig 1: Identifying Auxiliary Key
Courtesy of MAZDA MOTORS CORP.
Replace the cap using a flathead screwdriver, then rotate and remove the cap.
CAUTION:
- Do not turn the cap excessively. The cap may be damaged.
  
  Fig 2: Removing Cap
  Courtesy of MAZDA MOTORS CORP.
Insert a flathead screwdriver into the crack and press the battery out.

Fig 3: Removing Battery
Courtesy of MAZDA MOTORS CORP.
Insert the new battery (CR2025) with the positive pole (+) facing the (+) mark on the cap.
Battery specification

Lithium CR2025 x 1
NOTE:
- The batteries will last about 1 years when used 10 times a day.
  
  Fig 4: Inserting Battery
  Courtesy of MAZDA MOTORS CORP.
Rotate and close the cap.
Reinsert the auxiliary key.

Fig 5: Installing Auxiliary Key
Courtesy of MAZDA MOTORS CORP.