Sedan Model

Disconnect the ground cable from battery and wait for at least 60 seconds before starting work.
CAUTION: The airbag system is fitted with a backup power supply. After disconnecting the battery ground cable, the airbag may operate if you do not wait for 60 seconds before starting the service of airbag system.
Remove the rear seat cushion assembly.
1. Pull up the seat cushion and release the hook.
  CAUTION: If the hook is disconnected from the vehicle body, replace the hook with the new part to prevent the decline of the fixed force of the seat.
  
  Fig 1: Identifying Rear Seat Cushion Assembly Hook
  Courtesy of SUBARU OF AMERICA, INC.
  
  Fig 2: Removing Rear Seat Cushion Assembly
  Courtesy of SUBARU OF AMERICA, INC.
2. Remove the hook (A) by pushing it back while lifting the front side of the seat cushion, and remove the seat cushion assembly.
  
  Fig 3: Removing Seat Cushion Assembly Hook
  Courtesy of SUBARU OF AMERICA, INC.
Release the clips and claws, and then remove the side sill cover - rear INN. (On the side where airbag sensor is removed)
CAUTION: Do not pull with excessive force. Doing so may damage the claws of the side sill cover INN.

Fig 4: Removing Side Sill Cover - Rear INN
Courtesy of SUBARU OF AMERICA, INC.

NOTE: To release the claws of the side sill cover INN, the following steps are recommended.
1. Take out the weather strip from under the side sill cover INN.
2. Turn over the floor mat and release the claw (C-C and D-D) by accessing from behind the side sill cover INN.
Remove the rear quarter trim LWR. (On the side where airbag sensor is removed)
1. Remove the backrest side pad.
  1. Remove the screws.
    Preparation tool:
    
    Stubby screwdriver
  2. Turn over the bottom end of the backrest side pad in the forward direction so that the claws are released.
  3. Remove the backrest side pad by pulling it up.
    
    Fig 5: Removing Backrest Side Pad
    Courtesy of SUBARU OF AMERICA, INC.
2. Pull the release lever in the trunk room, and then tilt the backrest forward.
  
  Fig 6: Tilting Backrest Forward
  Courtesy of SUBARU OF AMERICA, INC.
3. Release the clips of the trunk trim panel assembly - side.
4. Remove the clips, and remove the rear quarter trim LWR.
  
  Fig 7: Identifying Rear Quarter Trim LWR Fixing Clips
  Courtesy of SUBARU OF AMERICA, INC.
Remove the nut and then remove the curtain airbag sensor assembly.
1. Push the lock arm.
2. Holding outer part, pull it one step in the direction of arrow.
3. Push the lock arm again.
4. Holding outer part, pull it in the direction of arrow to disconnect the connector.
  
  Fig 8: Removing Curtain Airbag Sensor Assembly Connector
  Courtesy of SUBARU OF AMERICA, INC.