All cheats should be entered during normal gameplay. To do this, bring up Niko's cellphone, use the table to find the cheat you want, and enter it using the directional keypad. Once the cheat is entered, a 'Cheat Activated' message will appear.
___________________________________________________________________________________________________


Health & Weapons
Give Niko health and weapons. 482-555-0100

Health & Armour
Give Niko health and armour. Blocks the achievement "Finish Him." 362-555-0100

Weapons (Advanced)
Baseball Bat, Grenades, Combat Pistol, Combat Shotgun, SMG, Carbine Rifle, Combat Sniper, RPG. 486-555-0100

Weapons (Poor)
Knife, Molotovs, Pistol, Pump Shotgun, Micro SMG, Assault Rifle, Combat Sniper, RPG. 486-555-0150

Remove Wanted Level
Remove any police wanted level. Blocks the achievement "Walked free." 267-555-0100

Raise Wanted Level
Add one star to Niko's wanted level: 267-555-0150

Change Weather
Select from eight different weather types: 468-555-0100

Spawn Annihilator
Spawn an Annihilator helicopter in front of Niko: 359-555-0100

Spawn Jetmax
Spawn a Jetmax boat in front of Niko: 938-555-0100

Spawn NRG-900
Spawn an NRG-900 bike in front of Niko: 625-555-0100

Spawn Sanchez
Spawn a Sanchez bike in front of Niko: 625-555-0150

Spawn FIB Buffalo
Spawn an FIB Buffalo in front of Niko: 227-555-0100

Spawn Comet
Spawn a Comet in front of Niko: 227-555-0175

Spawn Turismo
Spawn a Turismo in front of Niko: 227-555-0147

Spawn Cognoscenti
Spawn a Cognoscenti in front of Niko: 227-555-0142

Spawn Super GT
Spawn a Super GT in front of Niko: 227-555-0168