jdeuel

Redtdi96,

The O2 sensor was totally black. I'll start checking for vacuum leaks today. We always used carb cleaner to spray around the lines and find the leaks, but then again, those were the small-block Chevy days! Thanks!

jdeuel

Well, $690 (including a cat) and 2 pre-tests later, my Carrera passed! The 15mph smog-dyno nox was 80! Thanks very much to everyone who responded, and thanks to Tom at Deutsche Motorsport for hooking me up with the 'cat guy'.
I've decided, after finding this site, that I'm going to keep the ol' 911...

vwsamba

glad to hear you got it sorted, for others if NOX is a little high driving the hell out of it for 30 mins and getting it as hot as possible before the test works like a charm..

Ed Hughes

Uh, this thread is 5 years old.

rusnak

Yeah this is an oldie but a goodie. I'd guess his O2 sensor failure caused the system to foul the cat.