97 LeSabre failed smog

My 97 Lesabre failed the smog test the other day. These were the readings that showed up.
CO2 O2
% % HC (PPM) CO(%) NO (PPM)
RPM Max Meas Max Meas Max Meas Max Meas
15mph 1768 15.10 0.24 51 1 0.48 0.0 419 828
25mph 1714 15.00 0.25 35 1 0.46 0.0 706 1107


Everything looked great until the NO(PPM) measurement was way too higMax Meas. h.
Can someone give me some advice on what I can do to bring my NO measurement down?

(that's weird, everything lined up before I posted this).

NO2 is caused more commonly by a bad egr system, either it is not working which would usually set a code or the internal passages are clogged. Very high engine temps are a less frequent cause.

NO2 is caused more commonly by a bad egr system, either it is not working which would usually set a code or the internal passages are clogged. Very high engine temps are a less frequent cause.
Thanks for the quick response.

Is there a way to test my egr system besides failing a smog test, or can I do something to clean it out?

You can confirm it's operation using a high line scanner,also you can remove it and clean it up and make sure the passages in the manifold are clear.

And, by the way, if the catalytic converter is the original, that may well have to be replaced, in addition to, clearning out the EGR and it's passage ways.

This made me think--does the 92 lesabre have the stupid EGR system, or is it just the OBDII vehicles?

I wanted to spray the sea foam creep cleaner inside the throttle body and was surprised to find this honeycomb looking screen when I removed the big hose that connects to the throttle body. I removed the snap ring but couldn't figure out how or even if this screen can be removed. Then I decided I would just remove the throttle body from the intake manifold but I couldn't figure out how to get the lower front nut off, it's really tucked in tight behind this brace. Does this throttle body screen come out or do I just spray through it?

Also, I removed and cleaned out my egr valve and it seems to be in good shape (not sticking or anything, and no codes).

Careful with the screen, just pry it out gently.

Yes, My 99 has the same kind of bracket holding the throttle body on. I couldnt figure out how to get the lower bolt off either. Eventually I just pulled the top of the bracket toward the front of the car. This partially loosened the bolt (luckily), and working the bracket back and forth I got it off. For reassembly, I ground a little slot in the bracket, so I could get an end wrench on the lower bolt.

Just thought I would let everyone know that I passed my smog test today.

I really believe that the sea foam treatment, combined with removing and cleaning the egr valve and changing the oil 500 miles later (which are the only things that I did) is what made the difference.

My NO #'s went from 828 (low rpm) and 1127 (high rpm) to 167 and 224.

Thanks to all who gave advice and to automotive forums for being the great resource that it is.

Good news, thanks for posting back