From GTPlanet Game Guides

Gameshark Codes

Please be aware that not all cheats, hints and codes will work on all systems.

(M)must be on:
EC87829C1437062C

10 Trillion Dollars:
1C0411241456DEAD
1C041120D26487A5

Simulation Day 9999:
1C0411101456089C

Always Simulation Day 1 (DO NOT USE WITH Simulation Day 9999):
1C0411101456E7A6

Low License Times:
0d6a785c142617a5
1d6a785c145617a5

Want to do an illegal (meaning it wouldn't've been allowed if it wasn't a gameshark code) hp boost for a normal car race? Well, you can multiply your horse power of the cars in the top 20 slots of your garage by up to 60!!! Just enter these codes and you will have a decent hp boost. Just as an example, if you have a car with about 470hp and you use the "HP X 30" code, the car will have about 13,000hp!!!!!

The ????? will be replaced by a 5 digit code to add on to the end of the code.

slot #-

01-1C041208 145?????
02-1C041738 145?????
03-1C041968 145?????
04-1C041B98 145?????
05-1C041DC8 145?????
06-1C041FF8 145?????
07-1C042028 145?????
08-1C042258 145?????
09-1C042488 145?????
10-1C0426B8 145?????
12-1C042A18 145?????
13-1C042F48 145?????
14-1C043178 145?????
15-1C0433A8 145?????
16-1C0435D8 145?????
17-1C043708 145?????
18-1C043838 145?????
19-1C043A68 145?????
20-1C043C98 145?????

# hp is multiplied by-what ????? equals

02.03-6E800
04.06-6E0F3
06.09-6D8E6
08.12-6D039
10.15-60834
12.18-60027
14.20-6F87A
16.24-6F06D
18.26-62868
20.29-620BB
30.44-639DD
32.47-63158
40.59-65169
50.74-6AA18
60.??-5B00C

Use this code for Must Be On:
EC878298
1456E60A

Tons of Cash:
1C04BA20
1DBC9E0C

GT Moon Jump:
L1 0CB94166
1456B0FC
3D6E6FDB
1456E765

All B Liceneses:
1C02B058
1456E7A5
1C02B3AC
1456E7A5
1C02B200
1456E7A5
1C02B454
1456E7A5
1C02B7A8
1456E7A5
1C02B6FC
1456E7A5
1C02B850
1456E7A5
1C02BBA4
1456E7A5

All A Licenses:
1C02BAF8
1456E7A5
1C02BC4C
1456E7A5
1C02BFA0
1456E7A5
1C02BEF4
1456E7A5
1C02C048
1456E7A5
1C02C39C
1456E7A5
1C02C2F0
1456E7A5
1C02C444
1456E7A5

All IB Licenses:
1C02C798
1456E7A5
1C02C6EC
1456E7A5
1C02C840
1456E7A5
1C02CB94
1456E7A5
1C02CAE8
1456E7A5
1C02CC3C
1456E7A5
1C02CF90
1456E7A5
1C02CEE4
1456E7A5

All IA Licenses:
1C02D038
1456E7A5
1C02D38C
1456E7A5
1C02D2E0
1456E7A5
1C02D434
1456E7A5
1C02D788
1456E7A5
1C02D6DC
1456E7A5
1C02D830
1456E7A5
1C02DB84
1456E7A5

All S Licenses:
1C02DAD8
1456E7A5
1C02DC2C
1456E7A5
1C02DF80
1456E7A5
1C02DED4
1456E7A5
1C02E028
1456E7A5
1C02E37C
1456E7A5
1C02E2D0
1456E7A5
1C02E524
1456E7A5

All R Licenses:
1C02E778
1456E7A5
1C02E6CC
1456E7A5
1C02E920
1456E7A5
1C02EB74
1456E7A5
1C02EAC8
1456E7A5
1C02ED1C
1456E7A5
1C02EF70
1456E7A5
1C02EEC4
1456E7A5

(Stop Timer - License Mode Only):
0D6A785C
142617A5
1D6A785C 1
45617A5

(No Tire Wear):
1D6E6A885AC227A5
1D6E6D2C5AC227A5
1D6E6DD05AC227A5
1D6E6C745AC227A5