Game codes are found in a number of ways in the Doom 3 enviromnent. The most common location for a code is on a character's PDA that you pick up along the way. It will be either in an Email or on an Audio Log in that case.
There are a couple of other ways of finding codes. In one case a code is written on the side of a desk or filing cabinet or even displayed on a laptop.
The main use of a discovered code is to open a locked Storage Locker. The locker may be in the room or nearby in the level. However, in some cases the locker is in a later level - .e.g. Nick Sadowayj's Storage Locker 003.
Other uses for a discovered code is to unlock certain doors, unlock an airlock, or in one instance you need a code to restart a valve from an operations terminal. Again, the code you find may not be used for several levels, for instance you find the code for the BFG locked in M. Abrams Office several levels before finding his office.
Below is a table of all codes found in the game, where they are found, and how and where they are used. It is designed as an easy reference for quick lookup.
The table is listed in the chronological order in which you use the code, not when you find the code, that order is sometimes different because you may find a code much earlier than when you use it.
Where The Code Is Used
Who/What Provided The Information
Locker 001 396 Mars City: Maintenance Adam E. Berneche - Audio Log - Maintenance Update Locker 023 531 Mars City Underground: Energy Stabilization Unit Grant F. Baston - Email - UPDATED SECURITY CODE Failure Code for Operations Terminal 842 Mars City Underground: Energy Processing  Frank A. Delahue - Audio Log - Fire Blast Precautions Locker 017 347 Mars City 2: Infirmary Marcus T. Caseon - Audio Log - Patient Attack Weapons Storage Code In Marine Command 584 Mars City 2: Combat Preparation Sergeant Bill Tyson - Email - Security Code Change Locker 013 586 Administration: Alpha Labs Hallway Alan E. Dorweiler - Email - Armaments in the cabinet Free Stuff Martian Buddy 0508 Administration: North Hallway Alan E. Dorweiler - Email - Lightspeed Pharmacy Locker 009 752 Alpha Labs Sector 1: EPD Lab Kyle C. Berger - Audio Log - EPD Accident Locker 038 409 Alpha Labs Sector 2: MFS Compressor  Andrew Chin - Email - Storage cabinet 038 Locker 039 102 Alpha Labs Sector 2: Coolant Control Junction Walter I. Connors - Email - Note to self Locker 047 123 Alpha Labs Sector 3: Hazardous Materials Lift Mark B. Lamia - Audio Log - Incompetent Employees Locker 048 123 Alpha Labs Sector 3: Coolant Monitoring Mark B. Lamia - Audio Log - Incompetent Employees Locker 049 123 Alpha Labs Sector 3: EFR Staging Room 1B Mark B. Lamia - Audio Log - Incompetent Employees Locker 064 651 Alpha Labs Sector 4: EFR Master Valve Henry Q. Nelson - Email - Missing Tools Locker 063 972 EnPro Plant: Power Core Access Theresa M. Chasar - Audio Log - Weapon Research Plasma Storage Room Code 734 EnPro Plant: Maintenance 3 Steve L. Hammer - Audio Log - Plasma Ammo Code Locker 054 246 Communications: Security Office Ben B. Wolf - Email - RE: Request Security Access Locker 003 483 Recycling Sector 2: Monorail Access Nick Sadowayj - Email - Locked Armaments
Scott P. Johnson - Email - RE: Locked Armaments
Locker 054 (2nd) 142 Monorail: Site 2 Boarding Platform  Charles Hollies - Email - Remaining Ammunition Code For Monorail Airlock Junction 05 826 Monorail: Site 2 Boarding Platform  Gary Ross - Email - RE: Airlock Request Locker 078 364 Monorail: Delta Checkpoint Storage Karl P. Cullen - Email - Extra Medical Supplies Locker 079 364 Monorail: Delta Checkpoint Storage Karl P. Cullen - Email - Extra Medical Supplies Locker 21D 298 Delta Labs Level 1: Storage Room 21-D Robert M. Price - Audio Log - Disciplinary Action Report Locker 112 538 Delta Labs Level 2A: Records Office Frank A. Cinder's - Email - your lunch Chief M. Abrams' Office 931 Delta Labs Level 2A: Office M. Abrams Michael G. Abrams - Audio Log - Security Report
Michael G. Abrams - Email - Invalid Number in code
Locker 116 972 Delta Labs Level 2A: Delta Security Delta Labs Level 2A: Delta Security - On A Laptop In The Same Room Locker 114 715 Delta Labs Level 2A: Operations Server Room Delta Labs Level 2A: Operations Server Room - Post-it note on right of locker Locker 103 259 Delta Labs Level 2B: Maintenance Corridor Francis R. Erikson - Email - Locker code change request Locker 216 624 Delta Labs Level 2B: Specimen Research Lab Delta Labs Level 2B: Specimen Research Lab - Dr Michaels Locker 217 624 Delta Labs Level 2B: Specimen Research Lab Delta Labs Level 2B: Specimen Research Lab - Dr Michaels Locker 213 371 Delta Labs Level 2B: Stasis Transfer Control Jacob L. Stemmons - Email - Storage Locker Update Locker 666 372 Delta Labs Level 2B: Analysis Control Delta Labs Level 2B: Analysis Control - On post-it note on front of locker Door code for Storage 07 725 Delta Labs Level 2B: Central Processing  Elizabeth A. McNeil - Email - Storage room code changes Door code for Level 3 Access 463 Delta Labs Level 2B: Central Processing  Elizabeth A. McNeil - Email - Level 3 Access Code Change Free Stuff Martian Buddy (2nd) 0508 Delta Labs Level 2B: Secure Storage Alan E. Dorweiler - Email - Lightspeed Pharmacy Locker 386 836 Delta Labs Level 3: T1 Access Han M. Lee - Email - Security Team info Locker 387 836 Delta Labs Level 3: T1 Access Han M. Lee - Email - Security Team info Locker 317 841 Delta Labs Level 3: Terminal Office Storage Frank Z. Cerano, Ph.D - Email - Assistance Request Locker 104 579 Delta Labs Level 4: Delta4 Security Jack Gilbert - Email - Ammunition Cabinet
Delta Labs Level 4: Delta4 Security - On a laptop
Locker 452 571 Central Processing: Entrance Checkpoint Bruce L. Jackson - Email - Security Assignment Door code for CPU Lab A 627 Central Processing: Main Entrance Hall  Tony F. Bates - Email - Lab A Security Door
Central Processing: Security Monitoring  - On a Security Scanner
Locker 669 468 Central Processing: Lab A Upper Floors  Charlie D. Haskell - Email - How have you been?