Please note VGF's cheat codes have relocated to the main page.
Jimmy Neutron: Jet Fusion
Level Passwords
Level 2 - z91td?93
Level 3 - h9g!pzqg
Level 4 - d9f5Q?p3
Level 5 - 9!!jf93s
Level 9 - 31CX8442
Level 13 - 3P!76232
Mystery Level - 9!!8f93s
(Thanks to Athims@aol.com)