O2 hole/plug
 

Hey the header I bought had a slot for the O2 sensor so we installed it into there, and I have a O2 hole in my Cat as well, I was wondering if anyone knew what size bolt/plug I should get to plug the hole, cuz the exhaust is a bit loud w/ no plug in the Cat...

Anyone?!?!

M18 1.5

It took me awhile to figure that one out. It's called a UEGO plug or something. I had to buy a few of them myself.

Do you knwo where I can find one?

www.tuneyourengine.com or a plumbing supply store. You can also get a burned out o2 sensor from a salvage yard, cut off the wires, and use it as a plug.

Thanks!

You can go to just about any muffler shop and they can take care of it quick and cheap.

spark plugs have the same threads as an o2 sensor

Secondary O2 Sensor thread size
 

Could anyone tell me what the thread size of the secondary o2 sensor is or where I could find out? Ive been trying to find out for a while so I can get it drilled in my cat replacement pipe by the manufacturer. Ive got a JDM Prelude 2.2 Si Vtec (93) H22A

Is m18 1.5 the thread size?