O-2 Failure

[Paul Ruschman]

"THE" list,
I recently purchased a ECHLIN O-2 sensor and installed it in the collector of my Hooker Street Rod headers on my V-8 Datsun Z car. It worked great at first. I haven't been monitoring it lately and when I hooked my trusty Fluke 87 to the wires I ran in the car from the O-2 it was putting out between .18-.2 volts no matter what load/RPM. I looked at the O-2 sensor itself and  I noticed exhaust soot coming from the metal cap where the electrical lead comes out. I take it his is NOT good. 
	Any insight on this problem or experience using these generic one wire ECHLIN O-2 sensors? The parts guy at NAPA said it was a quality unit and recommended it over the generic BOSCH unit I originally wanted.

		Thanks in advance for any and all info,

		Paul (BRAAP) Ruschman
		75' 280 ZR-1
		http://www.datsuns.com/projects/paulrproject.htm