They just put that in to scare numpties into actually doing something.
Have a google for a complete list of fault codes for each of them. I'll bet there's an absolute fuckload of light-lit codes that aren't emissions related.
Which I take to mean you haven't got the faintest idea what you are talking about.
Tell us what the cars are, then, and I'll find you a list of non- emissions related fault codes that'll put this "emissions out of spec" light on.
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