Horn Removal/Installation

Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
Remove the set plate. (See SET PLATE REMOVAL/INSTALLATION .)
Remove the front bumper. (See FRONT BUMPER REMOVAL/INSTALLATION .)
Disconnect the connector.

Fig 1: Horn And Bolt With Torque Specifications
Courtesy of MAZDA MOTORS CORP.
Remove the bolt.
Remove the horn.
Install in the reverse order of removal.