I plugged my Impreza in today using a Bosch diagnostics system, 2000 reg classic, and it couldn't find any systems to check for engine codes.

Does the test wire have to be connected to allow for this, or shouldn't it matter, i'm saying this becuase the test wires are no longer present in my vehicle, they came out when i stripped the wiring loom down as it's a track car.

I'm going to try the Snap-on diagnostics tomorrow and see if that can pick anything up.

Thanks