2001 E430

I've had a number if issues with my CEL. I had a code for the EGR valve which I replaced, but still drive a CEL for it. The car occasionally exhibited signs of a sticking EGR, i.e. bad idle. That problem is gone, but I still drive the CEL P2001.

I had a code for a gross leak, so I changed the vent valve. Haven't had that code since I've changed that valve.

Now, occasionaly when I decelerate, my CEL pops up. I have a snapon mt2500 that indicates the code , p2001, is for EGR system malfunction.

I did a search on P2001, and found this thread:

Mercedes-Benz Diagnostic Trouble Codes (DTC) for 1996+ models #3

In that thread, it says P2001 is "P2001 NOx Trap Efficiency Below Threshold (Bank 2) ". Isn't a NOx trap for diesels?

Anyway, can somebody point me in the direction to solve this continueing issue? FWIW, the CEL goes away after about 15 starts.

__________________
Thank You!
Fred
2009 ML350
2004 SL600
2004 SL500
1996 SL600
2002 SLK32
2005 CLK320 cabrio
2003 ML350
1997 C280 Sport