I would like to help you guys with a simple explanation, but the truth is that I'm not very comfortable inspecting diesels either, and I don't want to post any incomplete or incorrect information. I have been stumped once or twice myself, and have wound up checking Motor ECSA, MostData and Google images, and following my instincts.
The last diesels that I worked with on a daily basis were the old International 6.9L and 7.3L V-8s in the Ford E-350 Ambulances over twenty years ago. They had almost no emission controls back then, but I remember some of the 6.2L GMs had EGR.
Maybe there are other members here with diesel experience, who could share some links or other info.
ALLDATA and Google got me through the first years of Diesel testing. I don't have ALLDATA anymore and it really sucks. They are too greedy with the $125 a month online access, they wouldn't have such a bootleg problem with reasonable tech friendly prices. But it is the easiest and most thorough way of learning diesels fast.
You can also try Smognotes.com, not sure if its reliable for diesels though.
It would be nice if we could start our own vehicle reference look up table with pictures and what not here.
Important Note: This topic has been pinned to the top of the forum, and its scope has been changed to include all types of diesel inspection issues. Look carefully at the subject of each post (like the one immediately below) to avoid wallowing in confusion.
Here's one I failed not too long ago. Push-rod type, Banks brand. Ford truck. aneroid compensator. Amazing what Mr Google does when I researched the brand name that led me directly to Banks' website with full description and no CARB support.
... For what it's worth, they will typically be found on mechanical injection systems. The newer HEUI (Hydraulically actuated Electronically controlled Unit Injection) and piezoelectric common rail injection systems will typically not use an aneroid compensator since they more often use MAP of MAF sensors to determine air flow.
Hmm ... I've been looking around a bit, and I think that your point is valid. My questions would then be as follows:
1) How many mechanical injection systems are subject to smog check? My guess is not many.
2) Of all the things that the OIS could prompt for, why this (rather obscure) item?
3) Is this some sort of test to see if we're paying attention? For example, if we enter "Pass" instead of "N/A" for a vehicle with no aneroid compensator, are we broadcasting our ignorance, and leaving ourselves open for a reprimand or citation for entering incorrect information?
man all of us having trouble distinguishing diesel cats, when their is a tech out there who ran a 2500 HD 6.0 gas as a diesel customer had paper work of 2 years ago, manual entry 2500 diesel vir showed visulal and obd only!
i was stumble when i seen it selected as diesel!