Many Questions On A Failed Emissions Test : P1406 Code

[96RS Alex]

P1406 is the extracted generic code according to the certified mechanic and his diagnostic machine. The minute I pulled into the smog test station the SES light pops on, just my luck.
Before all of this, I did fill the tank with midgrade 91 with 2 bottles of dry gas and ran the Camaro hard on the highways to get the cat nice and hot before this test.

Tonight I performed a 'Search' here and now I have a question.
I am more than willing to throw money at this problem but would it be sensible to replace the EGR valve & ALL the 02 sensors installed on my '96 L36 3800 Camaro? Last time I peeked under my car during an oil change, I think there are three 02 sensors ( 1 on each bank of the exhaust manifolds and 1 before or after the cat for a total of 3? ) and would someone please verify this for me?

I have also noticed that during extreme cold weather temps, my "regular" SES & ABS INOP lights stay off which is confusing to me but during the January warm spell we had here in the Northeast, them two lights lit up like a Christmas tree. My next free retest is Feb 23rd and Im debating on where to start.

Spark plugs were changed last summer at 190K.
Air Filter, Oil , PCV Valve done at 200K
Fuel Filter not done yet, but the idle is running smooth. 1 entire can of Seafoam poured in the gas tank last week before the emissions test.
201,500 miles on it now. I have attempted to be detailed about it as possible so bring it on.
Thanks in advance!

[v6man]

there are 4 total o2 sensors. if you want to replace the egr i would go ahead and do it. but i do not see a reason for replacing all the o2 sensors unless they been on the car since you bought it or they are like 100,000 miles old. and from what i understand the egr only operates at a certin throttle position and temp. (correct me if i am wrong) that is all i have sorry if it wasnt to much help.

[96RS Alex]

I believe the 02 sensors are the originals and have over 200K miles on them. Guess I got the best service life out of them. OK thanks V6man, this is a helpful start! More answers from everyone would be great too.

I am trying to access a catalog through GM Parts Direct so I can retrieve a part number for the EGR valve but I get the runaround on their website here http://www.gmpartsdirect.com/partsvoice/frameset.cfm

Am I doing this wrong or what? Sometimes this particular site is down at odd times after midnight.

[v6man]

wells egr1075 at autozone for about 135.00

[grayman]

um, why did you put higher octane gas in your car? unless you adjusted the timing it will not burn properly.

you might want to read up on gas grades and our modern ingition systems. your emessions mechanic did not mention this?

[96RS Alex]

Thanks for the comment Grayman.
The emissions mechanic has not asked me yet what grade of gas I was using but I will mention this to him. Connecticut revamped their emissions practices to just about any mechanic shop that participates in the state mandated program. Just pull in for the smog test and pull out a $20. It used to be state run emissions with their own facilities until it was found that most of the emission testers back then was found guilty of taking cash bribes from people who wanted a "Pass" sticker. It was that easy until CT suspended this unnecessary program.

Why did I purchase the midgrade? I decided price was a factor since my neighborhood was having an all out price war on fuel so I thought about jumping in on the savings. The price per gallon of midgrade was advertised at $2.29 vs the other competitor being much higher and the winner was Shell vs Exxon. If the adjusted timing was a known issue to me, I would have bet the computer would have been far ahead of me of the timing game in letting me know. I will try the 87 octane after the EGR valve is swapped for a new one with the possibility of all 02 sensors to see what happens.