Code: Lyoko on the tower interface.
|First appearance|| X.A.N.A. Awakens Part 2 (chronologically)|
|Purpose||Deactivates a tower controlled by X.A.N.A.|
Code: Lyoko is the code entered in any Tower to deactivate it. Once entered, it triggers a deactivation which stops and exterminates X.A.N.A.'s attacks. Before Code Lyoko Evolution, Aelita was the only one who could enter this code. This code has been entered in every tower at least once.
The code is entered by entering the tower, ascending to the upper platform, going to the terminal, and placing a palm on the terminal.
During season 5, Ulrich, Yumi and Odd also managed to deactivate the tower because of the source codes they had. Even though X.A.N.A.'s spectres stole these codes and Odd lost over 70% of them and the tower couldn't recognize who he was, he could still enter Code Lyoko.
Once the code is entered, all effects of the tower freeze, no matter how absurd. For example, if a tower is used to materialize a monster, and the monster is shooting a laser when the tower is deactivated, the laser beam will freeze in mid-air. If the tower is being used to regulate a Spectre, then the spectre disperses.
Deactivation without code
In the episode Franz Hopper, X.A.N.A.-Franz Hopper said he could deactivate any tower on Lyoko without this code. It is unknown if deactivating towers remotely can be achieved or not. However, in the game Code Lyoko: Quest for Infinity, Jeremie deactivates the tower in the first mission from the lab.
X.A.N.A is notably the only one who doesn't use codes to deactivate towers.
- The show was most likely named after the code, as in seasons 1-2, it was the main purpose of each episode to get to the activated tower so Aelita could enter the code LYOKO, and stop the attack.