The information available from the computers has varied a lot from one vehicle to the next. Whether the mechanic who plugs in to read the information will know what it means probably (in most places) varies a lot more.

Most of the diagnostic stuff does prove helpful for "standard failures," but for anything "intermittent" the codes are mostly useless, and GM at least gave multiple warnings about not believing the computer under many circumstances - or at least they did a few years back.

There are lots of other reasonably common failure points that could contribute to the problem at hand; but like for computer problems, many are quite difficult to diagnose without "hands on" the machinery. There are too many likely "solutions" to know which ONE is right.

John