Cheats in GTA IV

In Grand Theft Auto IV, The Lost and Damned and The Ballad of Gay Tony, cheats are activated by typing the cheat phone number into Niko Bellic's, Johnny Klebitz's, Luis Fernando Lopez's mobile phone. After this has been done once, the cheat will be stored in the phone, and accessible from the "Cheats" menu there.

Be warned that entering some of these cheats in the game will disable certain achievements/trophies, so do so at your own risk. Accessing secrets is different from cheats, and will not affect the status of gameplay. There is no way to unblock the achievements except for re-loading the game without saving after the cheat has been activated. However if a player uses any of these cheats but still desires all the achievements, they can simply start a new game file and complete the first mission. Then there are no blocks on the achievements. Because of the way that cheats work, they may have undesired effects on gameplay, such as glitches.

Inputting cheats does not block the player from getting 100% completion, just achievements/trophies. Note that in the PS3 version of the game, reloading the game file will make the trophies available, provided the player does not use those cheats again during the new session.

GTA IV

 * Another cheat to get full health, armour, ammo and repair one's vehicle can be used if the player is driving the Mr. Tasty; cycle through the ice cream jingles (using the horn button) until the GTA IV theme plays, then call the ZiT Service (948-555-0100). Although not documented as such, this counts as a cheat and blocks achievements.
 * Note that outrunning cops who try to stop the player skipping islands when Niko is in a spawned Jetmax will NOT give the Walk Free achievement but can be obtained later on in the same save file after being killed.
 * If the player has completed all 30 of Stevie's Car theft missions, Stevie will pay cash for almost any car delivered to his garage. Using vehicle-spawning cheats, the player can exploit this arrangement for as much money as he or she wants.  Below are the prices of the (eligible) spawnable vehicles; keep in mind that this table is presuming that the car is just spawned and has not taken any damage.

The FIB Buffalo and the Jetmax are unsellable spawn vehicles. The Annihilator cannot fit in Stevie's garage.

Most cars have a low sale value, however driving gently into a wall (enough to scrape the paint) will dramatically improve the value of certain cars. For example, when the Cognoscenti is spawned and sold in perfect condition, Niko will get $8,000; scraping the car against the wall of the garage while entering will change the payout to the full retail value, $10,500 (some have reported the value further increasing to $10,800). Presumably this is a game bug.

The Lost and Damned
The downloadable content adds cheats to spawn new vehicles. These do not block any achievements or trophies. In addition, any of the cheats from the main game can be used, and do not block any achievements in The Lost and Damned.

This list of phone numbers can be found at The Lost's clubhouse in Acter, in the form of a flyer listing the vehicles either for sale or as a prize for a contest.

The Ballad of Gay Tony
These are the cheats introduced in The Ballad of Gay Tony.