There are two things that may be relevant, that I don't think I've mentioned yet.
First, is that I've only ever seen the CEL come on within a minute or two after starting the engine. If it's not on within that time, it doesn't come on for the rest of the drive. Since I've been using my new 3-Combo to monitor my car, I've only ever seen the P0402 appear as a PTC or a DTC within this same time frame, and I have so far not seen at all any other PTC or DTC than P0402.
Second, is something I've now noticed, looking at recorded results for several runs, in which I've run the tests on the TESTS tab.
There are two particular tests related to the EGR, one of which always fails. There is the EGRUPHDIS test, ?Exhaust Gas Recirculation Upstream DPFE Hose Disconnect?, which should have a minimum limit of 504 inches of water, and there is the EGRDNHDIS test, ?Exhaust Gas Recirculation Downstream DPFE Hose Disconnect?, which has a maximum limit of 4 inches of water. Apparently, this is some measurable parameter which should change when the EGR changes some mode, so that it is either less than 4, or greater than 504. In every single case, both of these measured parameters are the same number, which results in one of the two tests failing. In some cases, the number returned by both tests is less than 4, meaning that EGRDNHDIS passes, and EGRUPHDIS fails, while in some other cases, it is a number greater than 504, in which case EGRUPHDIS passes and EGRDNHDIS fails; in one case, it was a number in between, causing both tests to fail.
I'm not quite sure what the dignificance is of these parameters with respect to what is physically happening under my hood, but I think this seems to very clearly indicate a malfunction in the EGR itself. Perhaps there is something about this malfunction which is causing the CATRAT2 test to fail also, or perhaps the CATRAT2 failure is something else, not related to the EGR failures.
{I do hate spam, but that isn't really part of my email address. Remove the string ?HatesSpam? from the email address ?BobHatesSpam@blaylock.to? to email me. No advertisements. Spammers will be dealt with very harshly!}
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Moonlight Blue 1996 Mercury Mystique GS , Zetec engine, ATX. No mods. (Well, OK, one mod. Before I got rid of my previous car, a 1994 Tempo, I swapped radios. I liked the Tempo's radio better. That counts as a mod, doesn't it? I also kept one of my Tempo's wheels to use as a spare. I hate those stupid ?compact? spares that come with modern cars. Does this count as a mod? If so, I guess I have two mods. Replaced burned/melted blower switch and connector on 19 February 2002 with a 1P3T toggle switch from Marvac and a Molex connector from Rat Shack; I guess this now makes three mods.)
