How-to: add a spare key to Smart 452 Roadster-Coupe year 2004 with OBDSTAR X300 DP Plus key programmer.

Prepare a working key (3-button) and a new be to be programmed.

connect x300dp plus with vehicle via OBD port under the dashboard
Turn on ignition switch with the working key
In X300 DP plus select Immobilizer- Smart – Smart V31.11 – BR452 – Program Remote

This function is available by connecting the server. Enable network connection.

Confirm deletion of all existing keys

Confirm VIN

Switch ignition off, then press the Lock button twice on each key. Then switch ignition on again

Program success

Test both keys. All working.
Done.