I certainly agree with SB.
Getting a code is a simple matter....
But interpretation takes a thorough knowledge of the entire system and their inter-ralationship.
And that takes a person versed in both mechanics and electronics and there relationship..
And that usually is one with an Engineering Education..
and/or a very experienced diagnostic tech...

[ and they have some of those right here...]

So access to codes gives the DIYer a little edge when posting a querry/problem in that it gives the complaint a basic diagnostic direction for those replying..and a better understanding for anyone else interested in/following that post..