Seems you grasped well the hidden point in my post. The interpretation of those OBD-1 codes (for those of you familiar with LH2.4) lead people to replace expensive things like AMMs and injectors. Really, there could have been many simple causes for any of those numbers. This hose was just one example.

Now and then, I really wonder at the forced design of OBD-1. For example "rich or lean at part load." The system knows damned well whether it was rich or lean when the map was adapted out of range. Almost seems as if the obfuscation was a "work to rule" design meeting the letter of the law. I guess OBD-II was the pendulum swing in legislated technology, but for me it is only a guess, having never owned a vehicle that modern.

So, having swung the other way, the computer knows 90% of the time exactly what is wrong with your 21st century car, but the techs may be losing the basics in the bargain, resorting to part-swap diagnosis in those 10% cases.
--
Art Benstein near Baltimore

Always read stuff that will make you look good if you die in the middle of it.