Cheat mode
Select the "Code Entry" option at the "Extras" menu, then enter one of the following codes to activate the corresponding cheat function:

Infinite health
Enter "94677" as a code.

Infinite stealth
Enter "53467" as a code.

Infinite copper
Enter "23637" as a code.

Infinite Chi
Enter "24463" as a code.

Double damage
Enter "34743" as a code.

One-hit dishonor
Enter "54641" as a code.

All treasure maps
Enter "37437" as a code.

Character concept gallery
Enter "97831" as a code.

Easy experience
Whenever you are in battle you can go back later to get more experience.

Defeating the fire machine
This is the machine you must fight in order to find Katara. Dodge the fire bending. Try running left to right, then right to left. Continue this until you see a flashing light near it, then attack it. Hit it with Aang. You may use a Chi attack but just a plain attack should work just as well, however it takes time. You will have Saka (Katara's brother) fighting with you to do double damage. Once it has around a quarter of its HP gone, the machine will start throwing fire around. Keep a safe distance from this attack. It causes no real threat to your or your partner as long as you stay as far away as possible.