Cheat mode
While playing the game, press Up to display Niko's cell phone. Press Up again to access the keypad. Then, enter one of the following codes to activate the corresponding cheat function. Once a code has been entered correctly, a new "Cheats" menu option will be available on your phone, below "Options", where you can access the cheats without having to enter the phone number again. Note: Do not save the game after enabling a code to avoid unforeseen problems. Enabling some cheats will prevent the indicated achievement(s) from being earned. You can usually only spawn one vehicle at a time. Any previously spawned vehicles will disappear. However, if you spawn a vehicle, save the game, and load again, you can spawn another one and your original will not disappear. You must have it in your parking space in front of a safehouse or it will be gone before you have a chance to spawn another.

Full health and armor
Dial "3625550100" on the cell phone. If you enter this code while in a vehicle, it will also repair it. Note: This phone number translates to "DOC-555-0100". This code prevents the "Cleaned The Mean Streets", "Finish Him", "One Man Army", and "Walk Free" achievements from being earned.

Full health, armor, and ammunition
Dial "4825550100" on the cell phone. If you enter this code while in a vehicle, it will also repair it. Note: This phone number translates to "GTA-555-0100". This code prevents the "Cleaned The Mean Streets" achievement from being earned.

Weapons tier 1
Dial "4865550100" on the cell phone. This will unlock the baseball bat, handgun, shotgun, MP5, M4, sniper rifle, RPG, and grenades. Note: This phone number translates to "GUN-555-0150". This code prevents the "Cleaned The Mean Streets" achievement from being earned.

Weapons tier 2
Dial "4865550150" on the cell phone. This will unlock the knife, Molotov cocktails, handgun, shotgun, Uzi, AK47, sniper rifle, and RPG. Note: This phone number translates to "GUN-555-0100". This code prevents the "Cleaned The Mean Streets" achievement from being earned.

Remove Niko's wanted level
Dial "2675550100" on the cell phone. Note: This phone number translates to "COP-555-0100". This code prevents the "One Man Army" and "Walk Free" achievements from being earned.

Add one star to Niko's wanted level
Dial "2675550150" on the cell phone. Note: This phone number translates to "COP-555-0150".

Spawn Annihilator police helicopter
Dial "3595550100" on the cell phone. The Annihilator is armed with rockets. Note: This phone number translates to "FLY-555-0100". This code prevents the "One Man Army" and "Walk Free" achievements from being earned.

Spawn Cognoscenti
Dial "2275550142" on the cell phone. Note: This phone number translates to "CAR-555-0142".

Spawn Comet
Dial "2275550175" on the cell phone. Note: This phone number translates to "CAR-555-0175".

Spawn FBI Buffalo
Dial "2275550100" on the cell phone. Note: This phone number translates to "CAR-555-0100".

Spawn Jetmax
Dial "9385550100" on the cell phone. Note: This phone number translates to "WET-555-0100".

Spawn NRG-900
Dial "6255550100" on the cell phone. Note: This phone number translates to "MBK-555-0100".

Spawn Sanchez
Dial "6255550150" on the cell phone. Note: This phone number translates to "MBK-555-0150".

Spawn SuperGT
Dial "2275550168" on the cell phone. Note: This phone number translates to "CAR-555-0168".

Spawn Turismo
Dial "2275550147" on the cell phone. Note: This phone number translates to "CAR-555-0147".

Change weather and brightness
Dial "4685550100" on the cell phone. Note: This phone number translates to "HOT-555-0100".

The following codes require "The Lost And Damned" bonus downloadable content:

Spawn Burrito
Dial "8265550150" on the cell phone.

Spawn Double T bike
Dial "2455550125" on the cell phone.

Spawn Hakuchou bike
Dial "2455550199" on the cell phone.

Spawn Hexer bike
Dial "2455550150" on the cell phone.

Spawn Innovation bike
Dial "2455550100" on the cell phone.

Spawn Slamvan
Dial "8265550100" on the cell phone.

Remove ammunition limit (The Lost And Damned DLC)
Get a 100% game completion in "The Lost And Damned" bonus downloadable content.

Bonus weapons (The Lost And Damned DLC)
Successfully complete the indicated task to unlock the corresponding weapon at a safehouse:

Assault shotgun: Successfully complete 40 gang wars and the "Heavy Toll" mission.
Automatic pistol: Successfully complete 20 gang wars.
Carbine rifle: Successfully complete 30 gang wars.
Grenade launcher: Successfully complete 50 gang wars.
Sawed-off shotgun: Successfully complete 10 gang wars.
Successfully complete the indicated task to make the corresponding weapon deliverable by Jim:

Automatic pistol: Successfully complete the "Bad Cop Drop" mission.
Pipe bombs: Successfully complete the "Hit The Pipe" mission.

Free guns (The Lost And Damned DLC)
Successfully complete all gang wars to get free guns from Terry.

Bati 801 bike (The Lost And Damned DLC)
Successfully complete ten bike thefts for Angus. The Bati 801 bike will now be available for Clay to transport to you or can be found parked near a safehouse.

Hokachu bike (The Lost And Damned DLC)
Win twelve races in single player mode. The Hokachu bike will now be available for Clay to transport to you or can be found parked near a safehouse.

Innovation bike (The Lost And Damned DLC)
Shoot all fifty seagulls. The Innovation bike will now be available for Clay to transport to you or can be found parked near a safehouse.