Leaky injector question

[i2ice4m3]

Hi I thought i'd relocate this question.

I have an ecu code 45 and I can visually detect the leak-It is on the injector closest to the radiator. Many people on this forum fixed the leaky fuel injector with new o-rings. My question is: Does the ecu detect an external leak or an internal leak-where the gas leaks onto the intake manifold, for example, as opposed to injecting too much fuel into its corresponding cylinder?

I checked my spark plugs and they all have a light brownish color. This is normal, as I understand. I also have a EGR malfunction code, if it might have anything to do with it.

Thanksl! I've searched the forum and many people seem to have this problem. None of the posts address my question, unless i've missed something :P

:help