How do you program remote unit on 2003 opel astra 1.8?

To program a remote unit for a 2003 Opel Astra 1.8, first, sit in the car with all doors closed and insert the key into the ignition. Turn the key to the "On" position (without starting the engine) and then back to "Off" five times within ten seconds. After the fifth turn, leave the key in the "On" position; the car's central locking system will lock and unlock to indicate it is in programming mode. Finally, press any button on the remote to sync it, and the locks will cycle again to confirm successful programming.