It's good to trust your people, but I still get a copy of the diagnostic print out. That way I know what is going on with my car so that there aren't any surprises. You can google codes.

A code will not show up on the diagnostic if the system (transmission, engine, exhaust, etc) doesn't send codes to the electronic control unit (ECU). Outside of the ABS, bad brake shoes/pads are not going to be on the diagnostic.