Achievements are disabled when cheats are used.
A = A Button B = B Button X = X Button Y = Y Button RT = Right Trigger LT = Left Trigger
RB = Right Bumper LB = Left Bumper Up, Down, Left, Right = directional buttons on D-Pad

Effect Code
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Give Item: Parachute - Left, Right, LB, LT, RB, RT, RT, Left, Left, Right, LB
Player Cheat: Drunk - Y, Right, Right, Left, Right, X, B, Left
Player Cheat: Explosive Melee Attacks - Right, Left, A, Y, RB, B, B, B, LT
Player Cheat: Explosive Rounds - Right, X, A, Left, RB, RT, Left, Right, Right, LB, LB, LB
Player Cheat: Fast Run - Y, Left, Right, Right, LT, LB, X
Player Cheat: Flame Round - LB, RB, X, RB, Left, RT, RB, Left, Square, Right, LB, LB
Player Cheat: Recharge Special Ability - A, A, X, RB, LB, A, Right, Left, A
Player Cheat: Wanted Level - Lower - RB, RB, B, RT, Right, Left, Right, Left, Right, Left
Player Cheat: Wanted Level - Raise - RB, RB, B, RT, Left, Right, Left, Right, Left, Right
Spawn Vehicle: Buzzard - B, B, LB, B, B, B, LB, LT, RB, Y, B, Y
Spawn Vehicle: Caddy - B, LB, Left, RB, LT, A, RB, LB, B, A
Spawn Vehicle: Comet - RB, B, RT, Right, LB, LT, A, A, X, RB
Spawn Vehicle: Duster - Right ,Left, RB, RB, RB, Left, Y, Y, A, B, LB, LB
Spawn Vehicle: Limo - RT, Right, LT, Left, Left, RB, LB, B, Right
Spawn Vehicle: Rapid GT - RT, LB, B, Right, LB, RB, Right, Left, B, RT
Spawn Vehicle: Sanchez - B, A, LB, B, B, LB, B, RB, RT, LT, LB, LB
Spawn Vehicle: Stunt Plane - B, Right, LB, LT, Left, RB, LB, LB, Left, Left, A, Y
Spawn Vehicle: Trashmaster - B, RB, B, RB, Left, Left, RB, LB, B, Right
World Cheat: Change Weather - RT, A, LB, LB, LT, LT, LT, X
World Cheat: Slippery Streets - Y, RB, RB, Left, RB, LB, RT, LB
World Cheat: Slow Motion - Y, Left, Right, Right, X, RT, RB

Note: Enter the Weather cheat multiple times to toggle through rain, clouds, clear days and snow.
Note: Unlike GTA 4, you can spawn more than one vehicle at a time.