Okay.....one more time.
Do NOT compare to two years ago.
As converters " age ", they will become less effective at eating up HC & CO.
HC is normally elevated by ignition & mechanical problems, i.e. misfiring and oil consumption ( simplified ).
Are they testing idle & load ?
If they are, the load test should always be done first, as this will really heat the cat. converter.
Another problem with HC is, they are measuring in PARTS PER MILLION, and failing on a few parts, is just a rip-off.
Not being familiar with your state's regulations, my next question is, is there a " degradation " factor built in ?
2007 C 230 Sport.