where do I put the O2 sensor. Before the flange or after.

[MrOverCast]

Hey guys!

So im working on a project and im trying to figure out where the best place is to place the upstream O2 sensor.

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So my question is, it ok to put the sensor before the flange? (no holes where drilled) ive read about this on some articles and some said this will give a false reading and others said its find. any suggestions?

 

[evilunclegrimace]

It will not make a difference. Personally, I would put it after the flange in case it becomes necessary to remove the header for any reason.

 

[Erik the Awful]

I put mine behind the flange. Also, you can get weld-in bungs fairly cheap from Amazon. I recommend the stepped version so you can drill a hole, drop it in place, and weld. I bought a pack of ten several years ago. www.amazon.com/Oxygen-Sensor-Fitting-Plugs-Stepped/dp/B079V4V5JX/