(Credit to: Gamespot, Xbox Forums, PS Forums, GTA IV Official Guide.)
First we will start with the cheat codes, these work with both 360 and PS3 version, i will also state what achievements it deactivates for the 360, if you activate A cheat code that deactivates A certain cheat remember you will not be able to get that achievement unless you start A new game, so i suggest you get that achievement before putting in the code. The codes that do not say anything about deactivating cheats will not affect achievements.
Cheat Codes
Refill health
Dial "362-555-0100" into the cellphone. Note: This code deactivates the "Cleaned The Mean Streets", "Finish Him", "One Man Army", and "Walk Free" achievements.
Refill health and ammunition
Dial "482-555-0100" into the cellphone. Note: This code deactivates the "Cleaned The Mean Streets" achievement.
Weapons tier 1
Dial "486-555-0100" into the cellphone. This will unlock the baseball bat, handgun, shotgun, MP5, M4, sniper rifle, RPG, and grenades. Note: This code deactivates the "Cleaned The Mean Streets" achievement.
Weapons tier 2
Dial "486-555-0150" into the cellphone. This will unlock the knife, Molotov cocktails, handgun, shotgun, Uzi, AK47, sniper rifle, and RPG. Note: This code deactivates the "Cleaned The Mean Streets" achievement.
Remove Niko's wanted level
Dial "267-555-0100" into the cellphone. Note: This code deactivates the "One Man Army" and "Walk Free" achievements.
Spawn Annihilator Helicopter (Includes missles and machine guns)
Dial "359-555-0100" into the cellphone. Note: This code deactivates the "One Man Army" and "Walk Free" achievements.
Safe Codes:
Add one star to Niko's wanted level Dial "267-555-0150" into the cellphone.
Spawn Cognoscenti (Mafiya Sedan) Dial "227-555-0142" into the cellphone.
Spawn Comet (Car) Dial "227-555-0175" into the cellphone.
Spawn FBI Buffalo (Car) Dial "227-555-0100" into the cellphone.
Spawn Jetmax (Speed Boat) Dial "938-555-0100" into the cellphone.
Spawn NRG-900 (Motorcycle) Dial "625-555-0100" into the cellphone.
Spawn Sanchez (Dirt Bike) Dial "625-555-0150" into the cellphone.
Spawn SuperGT (Sports Car) Dial "227-555-0168" into the cellphone.
Spawn Turismo (Sports Car) Dial "227-555-0147" into the cellphone.
Change weather and brightness Dial "468-555-0100" into the cellphone.
100% Completion requirements
* Missions - Complete every Main Story and Procedural Mission (90 total)
* Car Thefts - Deliver all 30 vehicles to the garage
* Friends - Open all unique abilities and complete all activities for all five friends (except Roman & Dwayne)
* Activities - Beat the computer or an ingame friend at all activities at least once.
* Random Characters - Find all 14 RCs and complete their encounter missions (except Jeff, Cherise, Clarence, & Ivan)
* Most Wanted - Kill all 30 PEDS on the list.
* Vigilante - Complete 20 crimes (they do not have to be consecutively)
* Flying Rats - Find/Kill all 200 pigeons
* Unique Stunt Jumps - Complete all 50 jumps
Note: Must do all in single player, does not count it multiplayer.
(This map below can be used to help find weapons, stunt jumps, flying rats, vehicles, etc. credit to google.)
Tips & Hints
Easy money
Go to an ATM, then cause a traffic jam to the area. Wait for someone to take money from the ATM, then kill him or her. Make sure to block any nearby roads so the ambulance cannot get to the murdered victim. Take the money they dropped on the ground. Then, run a short distance away, and go back. The money should have respawned on the ground. You can repeat this as many times as desired. You can also kill more people taking their money from the ATM to increase the amount of money that respawns. -From: Khairol161
Perfect Bowling Strikes
pick the first lane take 2 full steps to the left pull back the right stick and count to one (don't rush it take your time) then push up on 2 do NOT add after-touch.
Repairing engine
If the vehicle you are driving breaks down and the engine will not start, call 911, and your engine should start again.
Parking more vehicles at safe houses
Outside your first safehouse is a small parking area to park your vehicles and save them. Instead of parking your vehicles fully within the lines, you can park your vehicles partially within the lines to allow for more vehicles to be parked and saved.
Fast travel
To avoid wasting time driving all the way across the city, call a taxi. They will take you to your destination for your mission, stores, safehouses, or even a waypoint marker. You can skip through the taxi ride, allowing you to travel across the entire city in about ten seconds. This can also be done during missions.
Easy headshots
It is sometimes difficult to get headshots, which do count. With some practice, doing the following is an easy way to get headshots. Press [Auto-Aim], then use the Right Analog-stick to move the auto-aim target around your victim's body. Barely move the Right Analog-stick as you are shooting. This puts bullets in the chest and head, and results in an easy instant kill.
Getting away from police
When running away from the cops, you will have a circular area in which they look for you. However, if you get out and another cop sees you, it changes. To use this to your advantage, barely get out of that circle, which you will see on your radar. Then, just sit there for about five seconds instead of flooring past it.
Calling for Backup
Steal a police car and any time you are in trouble press L1 while your car is stationary. Select “Call For Backup” and within minutes you will have to cruisers full of police who will fight on your side unless you shoot someone.
Regaining health during missions
You can leave the mission area and go to a Cluckin' Bell, hotdog stand, etc. and eat food to replenish your health if you are low and cannot find a health pack. This is especially useful on missions where there are no health packs in sight. Note: You can also take a taxi to those locations during missions.
Avoiding toll booths
Drive through any toll booth with any emergency vehicle with the sirens on. The booth attendant will open the gate, and you will save $5.
$100 for all ringtones and themes
After getting the phone from Playboy X, go to the nearest Internet cafe. Buy all of the ringtones and themes from the ringtones site. Log out of the computer, and you will notice that you only paid $100 for all ringtones and themes.
Easy "One Man Army" achievement
Go to the bridge that takes you to the second island and has a train track under it. Walk along the train track towards the second island before you are allowed to cross the bridge. When you are about half way, you should have a six start wanted level. Then, just stand on the train track for five minutes to get the achievement. You do not have to worry about the police because they will be on the bridge above you so they cannot shoot, and the helicopters are above you so you have cover from them.
Ricky Gervais Cameo
Take a friend (Packie or Jacob works) to the Comedy Club in Star Junction (central island) and Ricky will perform a stand up routine.
Police database
On the LCPD Internet page there's a tab at the bottom of the home page which says "DATABASE". Click it and you'll be able to get info on all characters in the game including Roman and Niko.
Music info
Dial ZIT-555-0100 and you'll get a text message of the title and artist of the current music playing.
Get Helicopter with rockets
Collect all 200 pigeons (flying rats) to unlock a helicopter with rockets.
MISCELLANEOUS
Prank Calls
Here's something funny to try. During your adventure through Liberty City, you may find phone numbers written in inconspicuous places, such as on the side of a building or in the subway. If you dial these numbers, you'll usually get someone on the other end who you can subsequently prank.
Statue of Happiness Beating Heart
Head to the Statue of Happiness on Happiness Island via helicopter. Have the helicopter drop you off on the very top of the statue. You'll find a sign up there that states "No Hidden Content Beyond This Point", but it's a lie. If you head inside of the statue from this area, you'll find an actual beating heart inside the statue.
Fire Truck Madness
If you boost a fire truck, press the fire button while driving around. This will allow you to shoot the super-powerful water cannon at anyone around you.
FRIENDSHIP BONUSES
Reach the indicated level of friendship with the corresponding character to unlock their special friendship ability:
Brucie
-Likes: Bowling, drinking, eating, strip clubs, shows, helirides, boating
Special ability: Unlocked at 70%. Call Brucie and he will fly his chopper to you, allowing you to fast travel to various portions of the city.
Dwayne
-Likes: Strip clubs, eating, drinking, shows, bowling
Special ability: Unlocked at 60%. Call Dwayne for a car full of gang members that will follow you.
Packie
-Likes: Strip clubs, shows, darts, drinking, bowling, pool
Special ability: Unlocked at 75%. Call Packie and he will make you a car bomb.
Little Jacob
-Likes: Darts, shows, pool, drinking, eating, strip clubs
Special ability: Unlocked at 60%. Call Little Jacob and he will drive out a car full of guns for you to buy.
Roman
-Likes: Bowling, darts, drinking, eating, pool, shows, strip club
Special ability: Unlocked at 60%. Call Roman and he will send a cab for no charge.
Easy Achievements.
(One Man Army) Go to some water or what ever, if there is a island you can't cross yet then use the Jet Max cheat code get in that boat and cross to that island, don't get off, you will get 6 stars, just keep driving the boat, stay within the wanted circle, if you leave it you may lose the cops then you will have to start all over.
(Walk Free) Simply go to the airport you will get 4 stars, do the boat cheat code as in one man army, then jump in and drive away til you lose them, this is faster then trying it in a car.
Google Maps style GTA IV Map:
GTA 4 Liberty City Map Images and Screenshots
Moon Lander Champion!
Yeti Pentathlon Champion!
Linear Mode
