Here is the critical warning every guide must mention.
: Return to the Codebreaker interface and select Start Game (often by pressing 'X'). The game will boot with the cheats sideloaded. On Physical Hardware (Free McBoot/OPL) Codebreaker V10.1 Ps2 Iso
Always back up your memory card via Codebreaker before using new cheats. Infinite health is fun; corrupted saves are not. Here is the critical warning every guide must mention