You have high NO which indicates the EGR system is not flowing to reduce combustion temperatures on your first 15mph test..

High combustion temperatures produce high NO.
You need to find out if the vacuum hoses and the EGR valve are functioning.

CO indicates your cat's working okay but fuel mixture a little rich at low speed which might be a lazy O 2 sensor..
Was this an Enhanced test or a Basic. ?

We don't have Smog Checks here, but I think we ought to.


.

__________________
[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

I don't know which test it was. I had to go to a test only station which involves a dino in the process.

__________________
1992 Mercedes-Benz 400E
2002 Mercedes-Benz ML500

Clean out your EGR pipes, they get clogged. Replace the injector seals, rubber vacuum hoses/elbows and plastic vacuum lines. Check the catalytic converter to make sure it's not damaged.

__________________
Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.

I agree...clogged EGR tube last year got my 300E to fail for the first time!

After that, drive the s#it out of the car on the highway for a few days prior to retest.

There is some stuff you can buy in a tiny jug called de-carbonizer, that is sort of a "cheat sheet" way to help push along your emission results. Pour it into your tank, then drive around enough to get your cat heated up sufficiently before you get your smog test done.

Mine barely passed after that (didn't get to drive the living hell out of it before the test), but that's all you're gunning for anyway!

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

check out my thread

Smog check caught up with me


glenmore
1991 300CE
2000 C280
1990 LS400

Well it seems to me as if it's got to be the EGR valve and tube. I think I'll take a look at it and see what I can find.

As for the cat being the issue I don't think it's the issue anymore. I was under the car recently and inspected the whole exhaust system included the cat, from the outside there's absolutely no damage, not even any rust!

I'll let you all know what I find.

__________________
1992 Mercedes-Benz 400E
2002 Mercedes-Benz ML500

>>

I hope you do not assume a cat can be diagnosed as OK by looking at the outside of it....