So, I was compelled by the Great State of Ohio to get my biannual emissions test before renewing my plates, the other day. And while I really don't mind (especially since the test is free) other than the time spent at the testing facility, something gave me pause. Yes, she passed, but I had occasion to look at the test results and noted that the Nitrous Oxide level, while within spec, was at the high end of the scale (870 ppm on a max of 917 ppm). I asked my brother-in-law about these numbers (he's ASE certified in about 60 different fields and has been working on my vehicles for years) and after review of these and comparing them to the previous few tests, he indicated that the higher reading was indicative of the EGR slowly failing. He then explained the theory behind the EGR and gave me a thumbnail sketch of how it works. Very interesting, actually.

So, after all that, I took a look a the whole of the EGR system and noted that there seem to be a few components to the thing: The valve itself, and a couple of controllers. All fairly pricey, and all working as a system.

Query: Is there any one of those components that is more prone to failure than the others? Or, since it seems to be a case of "creeping deterioration" would I be best served by removing the whole thing and perhaps cleaning it, since many engine parts on this car seen to have a penchant for getting stuffed, clogged, plugged or otherwise just dirty enough to cause a drivability problem? Any suggestions welcome.

B