Go to the Special Functions screen.
Select Remote Keyless Entry.

Following Dialog Appears

• Turn ignition OFF and press button “Read” to get number of programmed smart keys.
  Press button “Erase” to erase all of programmed smart keys.
  Press button “Program” to program 1 smart key. You will be prompted to remove Key
  Cover and to place the key in emergency slot in the steering column shroud
  All of smart key operations must be performed while ignition is OFF.

Ford Mondeo 2016 for an exaple and other models have the following Emergency Key slot position

Manual reprogram a remote transmitter.
The following procedure has to be used to program the remote control key.

1.Turn ignition from OFF to RUN 4 times within 6 seconds with the 4-th time ending in OFF.
2.The system will chime to confirm programming mode entry.
3.Press any button on the first remote transmitter.
4.System will chime to confirm programming.
5.Repeat steps 2 and 4 for all subsequent remote transmitters.
6.Turn ignition to the RUN position to exit the programming mode.

Note:

• All keyfobs for the vehicle must be programmed at the same time. Any of the keyfobs which are not programmed during this procedure will no longer function.

• Up to 4 transmitters can be programmed.

Note: After programming Smart keys in Mazda, you may experience the “Keyless System Inspection Required” error message on the dash. This happens when keys that are intended for Mazda3, Mazda6 are programmed on Mazda CX3 and CX5 and vice versa. The only solution is to erase all Smart Keys and use the correct keys for the model. If there is even one wrong key programmed, the same error will show up. It has no effect on the overall performance of the car: