Just go this in yesterday to get rid of my P0420 code.



Now, is it possible to replace this on ramps? I don't want to get under to find out I cant get the old one out and the new one in. Or will I need a lift?

Also, what are the torque specs on the 3 manifold to cat bolts and 2 cat to exhaust bolts?

I'm also replacing the up stream O2 at this time. I tried to get it from the top, and maybe it was a bad angle, but couldn't seem to get it. I also need to pick up an O2 socket and it's seated into the manifold too far for a wrench to grap it. I'll be swapping the new downstream O2 when I pull the old cat out.

 

 

mine was a pain the butt to remove..and had to do it on a hoist..its really hard to get to the bolts on your back because you really have to reach..also ended up using a torch to heat up all the bolts to get them off

 

Real easy, unless you have to cut nuts. A 12" 1/2 extension with a swivel and air gun makes the header end easy. And WD40, or your favorite. You really don't NEED a special socket for the sensors, once you disconnect the wires.

First time I did it, very easy. Didn't use ant-seize on the tailpipe end because I figured "that's the next guy's problem"... but I was the next guy.

FWIW, GM says you are supposed to use their special glass bead sealant on the HO2 sensors. They also say to replace the studs and nuts. The 5 new nuts are about $9 each,... guess what?

And you will need the other gasket. The wife just rang the dinner bell so somebody else will have to get the torque specs, I use red neck specs.

From the 2006 manual:
Catalytic Converter Nut 34 lb.ft. (header end)
Exhaust Muffler Nut 34 lb.ft. (muffler end)
Manifold Heat shield nuts 16 lb.ft.
Drive shaft heat shield to engine nuts 22 lb.ft.
Drive shaft heat shield to trans axle nuts 89 lb.in.
Exhaust manifold heat shield stud 16 lb.ft.

Can't seem to find the HO2S torque specs.