Downstream O2 sensor, where to install it? Options

[bryanf]

My 1994 Celica ST (7A-FE) is now 25 years old so today's emissions test will be the last! Im celebrating with a new exhaust system.

I already got the eBay stainless header, which I plan to have ceramic coated. I would like to use an aftermarket cat.

Should I install the downstream O2 sensor before or after the cat? The guide shows installing it in the downpipe, but in this thread Box (where are you Box?) says to install it after the cat. And what if i don't use a cat?

I also wondered where to get the proper flange for the sensor.



This post has been edited by bryanf: Jul 14, 2024 - 11:08 AM

[Bitter]

Ok, you could probably just extend the 2nd O2 to after the main cat (tunnel cat) and it would work.

[bryanf]

Ok, you could probably just extend the 2nd O2 to after the main cat (tunnel cat) and it would work.

I was thinking about doing that! Thanks for the confirmation.



I've finished fitting the header to the head so it's almost ready to take for ceramic coating.

This post has been edited by bryanf: Jul 14, 2024 - 11:06 AM