Many new Citroen vehicles are equipped with remote locking using a "plip" (otherwise known as a key fob), so it is vital to be familiar and comfortable with this technology. Activating these plips are a case of knowing which buttons to press and the protocol to follow--if you do so then you should have no problems locking and accessing your Citroen.
Turn the ignition switch to the "accessory" position while the key is inserted, but without the remote plip attached.
Walk around to the front end of the car and press the plip key towards the receiver which is located at the front of the vehicle.
Press the large plip button on the remote, and then the small plip button immediately afterwards.
Repeat for a second plip key if your car is equipped with more than one plip for multiple user entry.
Turn the ignition off once you have completed the process for the amount of key plips you need.
Wait for five seconds, and you will now find that your plip is activated and will lock and unlock your car remotely.