The following are known Action Replay Codes for Top Gear GT Championship on Nintendo Game Boy Advance (GBA).
These codes were also known as GameShark Codes and in most cases will work on both devices.

These codes are for the U.S. version of the game.

Master Code – Must Be On
e8571309
829c49ee
1fe4973d
c6bb9b43

0 Lap Time
36df295c
0a116a7e

Max Clearance Points
1aa3a857
3accef90

Press AR Button: Slow
dbba3a89
4cb74b94