If you illiminate the EGR system wihout the "chip-tune" this code will be anyway, it will become your best friend and will always lit up your CE lamp. It can become a problem, 'cause you will not be able to determine visually, what codes do you have, and will have to read codes regulaly to ceap you car healthy.
And I really don't know (and the Service manual don't) what the other two means...