Rotten egg exhaust smell is indicative of a rich fuel mixture. Only thing that I would recommend, since I don't know too much about these things (yet) is to check the wiring, and any gadgets that it goes to from there. There is a post that is fairly new, that talks about the EHA and another device that it works with... it may be of help.
PS: also check to make sure you didn't accidentally knock off a vacuum line...I think there is one in that area. (I replaced my leaking EHA last year, and don't quite remember if there was a vacuum line in that area or not at this moment.)
"...rationality of thought imposes a limit on a person's concept of his relation to the cosmos." -Nash
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09 Jetta TDI