So it's not the 02 censors?

 

Catalytic Converter....

You likely need new ones or remove them and have the rear o2's turned off with a tune.

 

man this is so overwhelming, so should I just replace all the 02 censors & cat?

 

Since Pierce County, Washington does smog tests, you will need to start with replacing the rear oxygen sensors, then if the code continues replace the y-pipe. The OEM y-pipe is $1710.79 plus labor. Tuning the codes out of the computer is not possible as you will likely fail the smog test.

Now, you can get a non-CARB compliant y-pipe with cats for $656, but it's not nearly as pretty or as well flowing as the stock Y-pipe.

 

I plan on just buying the Magnaflow 23462 Direct Fit Bolt-On Catalytic Converter to replace the old 1 & also replace all my 02 censors.

 

That one won't fit your truck... you should be using the
Magnaflow 23453 for a 1999 Tahoe 5.7L

PS: It's "sensor" not "censor"

 

seriously, that's what they told me at Firestone..Well if possible would you know what kind of cat I would need? I have a 99 Tahoe 5.7 4X4

 

Edited my post too late lol.

 

So after looking under my truck I see that there are 3 bolts holding the cat in on each end of the cat, can I just buy the cat to replace or do I have to get the Magnaflow 23453?