2G After market Rear O2 sensor location

Myk984g63 · Nov 27, 2021

My rear O2 sensor is installed close to half way under the car, near the back of driver's seat from previous owner. Is that too far away for accurate readings for my wideband?

dustyboner · Nov 27, 2021

normally the rear o2 sensor is after the cat. i assume you still have the cat since your in cali. So as far i i know, it would be better to get a bung welded on the down pipe.

Myk984g63 · Nov 27, 2021

No cat. (I know a smog ninja) 3" catless from O2 housing back to a Agency power exhaust. It just seems like it's too far back for an accurate reading

jdxnc · Nov 27, 2021

If there's no cat and you still run a factory front o2, it will be fine. What you don't want is to be simulating the front o2 from that far back.

Myk984g63 · Nov 27, 2021

Okay I am simulating because my ext. wastegate is in the way to run a front O2 so the rear is my only one.

dustyboner · Nov 27, 2021

Myk984g63 said:
No cat. (I know a smog ninja) 3" catless from O2 housing back to a Agency power exhaust. It just seems like it's too far back for an accurate reading

screw smog. all it takes to figure out its a bunch of BS, is 5mins on google and a tiny bit of common sense. Co2 only makes up 0.04% of the atmosphere. Its not a problem. any lower and plants wouldn't grow for shit.

just make sure you don't have any leaks before the sensor.

here is a quote from innovate motorsports

Positioning the sensor too close to the exhaust ports can expose it to high exhaust gas temperature (EGT) as well as over-cooling from the high-velocity exhaust gas flowing over the sensor. Likewise, if an engine runs excessively rich, an oxygen sensor that’s positioned farther downstream is less prone to fouling. Although these extreme conditions aren’t a concern in most street applications, placing the sensor farther down the exhaust tract is rarely detrimental.

Myk984g63 · Nov 28, 2021

jdxnc said:
If there's no cat and you still run a factory front o2, it will be fine. What you don't want is to be simulating the front o2 from that far back.

So do I need to move it forward towards the downpipe Jason?

motomattx · Nov 28, 2021

Three feet from the head is recommended for wideband sensors.

Myk984g63 · Nov 29, 2021

motomattx said:
Three feet from the head is recommended for wideband sensors.

Then I'll be moving it ASAP. Thanks for the input everybody! Slowly getting it dialed in for a WOT tune. It's boosted to 10psi with no hiccups so far but don't want to push it harder than that for now. I'll update soon!

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2G After market Rear O2 sensor location

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