If the keyless remote battery or the vehicle battery is dead, use the key instead of the keyless remote.

Fully insert the key and turn it.
Locking/Unlocking the Doors Using a Key
When you lock the driver’s door with a key, all the other doors lock at the same time. When unlocking, the driver’s door unlocks first. Turn the key a second time within a few seconds to unlock the remaining doors.
Models with driver information interface
You can customize the door unlock mode setting.
Customized Features
Using the Remote Transmitter
Locking a Door Without Using a KeyHonda Civic Service Manual. Side Impact Sensor (First) Removal and Installation (4-door)
7521B6 LEFT FRONT
7521B7 RIGHT FRONT
NOTE: SRS components are located in this area. Review the SRS
component locations and the precautions and procedures before doing
repairs or service.
1.
Battery Terminal (SRS) - ...