Originally Posted by blackwrecks
Note this in reference to the WRX AP not necessarily the STi:
Anytime you reflash your ECU (or disconnect your battery for that matter), the car has to go through 50 or 60 cycles of turning off and on before the ODBII sensors are in a ready state.
The newest versions of the AccessPort BASE maps have a modification to the stock ECU code that will immediately put the sensors in the a ready state.
Most likely you're running and old base map with your accessport, or using a stock base map.
The base map I had been using since 11/15/04 was stage 1, 93 octane v1.18. This is their latest revision. I did not have a real time map loaded.