Is there a way to disconnect or bypass the downstream o2 sensor so I can run a high flow cat?

 

What do you hope to gain? Newer stock cats flow pretty darn well as is. You may not require any modifications to the rear O2 sensor.

As far as options, a spark plug anti-fouler can get the sensor up out of the exhaust stream a bit, smoothing out its response. You can also get the post-cat sensor removed from the PCM with a custom tune. Of course, these modifications would be for off-road use only as tampering with emissions devices on your vehicle is a federal crime...

 

I live in Tennessee we don't believe in good emissions haha
But anyway I was leading away from a custom tune because there is nobody close around here to do anything like that. I just want a better flowing exhaust, the cat is pretty rusty and crappy looking.

 

On my 98 i run a high flow cat and passed emissions no problem with the o2 still intact.

however i know somewhere online they sell an O2 that will give the computer a false reading so you can run whatever you want and still pass

 

We don't have an emissions test so nothing like that is a problem, what kind of high flow cat do you have?

 

its a magnaflow direct fit

 

Alright thank you

 

We don't have emissions here either, but just in case we ever do.
I removed the factory cat and gutted it and reinstalled it so it would pass a visual, but it threw a code P0420, bad cat.

I heard about the spark plug non fouler trick, but having to drill it and most people have to use two of them to get it up out of the exhaust stream to work, I didn't like that idea.

That's when I came across this on Ebay.

Oxygen sensor extender HHO HYDROGEN spacer Test Pipe O2 M18 X 1.5 thread size | eBay

No modification needed, has the right height, and it's only $3, Installed it and my SES light disappeared the same day.

 

Thanks for that, i'll buy one.