codes and how to diag. them on a 2002 A4?

I have a bentley cd but that does not have too much on fault codes and diag. of the codes.

Any help would be great... :)

So if you have a fault code it will tell you what it is.....

when i see a code with its description i want to look at something else and see how to trouble shoot that fault code. For example if i get a code 00011 and it give the description I then go look at my bentley or my fault code list and see some trouble shooting steps to take with that code. the techs must have something like this correct? thanks...