Post cat O2 sensor (S2 LS3)

[LJW-SVZ]

So quick question about o2 sensors on a VFII SS that I’m about to do headers on

So I’ve got myself a set of Xforce long tube headers (1 7/8”) for my car that I got off marketplace (image attached), issue with them is that they didn’t come with the cats. Not an issue for me per se because I’m a welder so I can just make my own to suit.

Since I don’t have the cat pipes to suit the car, what size o2 sensor socket will I need to install them in the car? And what sensor extensions do I need to use for the job, and I believe it’s a 22mm ring spanner job to remove the sensors?

 

[dassaur]

They are all m18x1.5
By the looks of those you will need front extensions. The rears may or may not need extensions depending where you put the cats.
Don't forget to get the rear 02s turned off in the tune before you install the headers (and I'm assuming high flow cats) otherwise you will have permanent dtc codes which can't be removed except by putting factory cats back.

 

[LJW-SVZ]

They are all m18x1.5
By the looks of those you will need front extensions. The rears may or may not need extensions depending where you put the cats.
Don't forget to get the rear 02s turned off in the tune before you install the headers (and I'm assuming high flow cats) otherwise you will have permanent dtc codes which can't be removed except by putting factory cats back.

Thanks for that mate. I’ll get on some extensions for the fronts and some sockets for the rear. I think Aeroflow sells some harnesses to suit the commodore plug? And I’ll need to have a chat with my tuner before I do it in that case, I had it tuned previously but I’m not sure if the post cat sensors were disabled or not

 

[Pazzu]

ooks of those you will need front extensions. The rears may or may not need extensions depending where you put the cats.
Don't forget to get the rear 02s turned off in the tune before you instal

This makes perfect sense as to why I have a permanent DTC code, i had to wait for a week before i could tune it and now it always there. Not annoying as CEL doesn;t turn on, but definitely wish that i didn't drive around for a week.

This then poses the question, if the Post Cat o2 sensors are going to be turned off... then is there any point even in installing them?

 

[dassaur]

Thanks for that mate. I’ll get on some extensions for the fronts and some sockets for the rear. I think Aeroflow sells some harnesses to suit the commodore plug? And I’ll need to have a chat with my tuner before I do it in that case, I had it tuned previously but I’m not sure if the post cat sensors were disabled or not

You could probably drive it to the tuner (as long as they're not ages away) and be ok, it doesnt show up instantly

 

[RevNev]

Don't forget to get the rear 02s turned off in the tune before you install the headers (and I'm assuming high flow cats) otherwise you will have permanent dtc codes which can't be removed except by putting factory cats back.

You've got to switch off Cat Efficiency. If you just switch off the post cat 02's, it'll still throw the Cat Efficiency CEL in VF2.

 

[dassaur]

You've got to switch off Cat Efficiency. If you just switch off the post cat 02's, it'll still throw the Cat Efficiency CEL in VF2.

Yes exactly, I kind of bundled it all in one

 

[07GTS]

the cat efficiency code can limit the engine so worth turning off asap