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O2 Sensor Placement

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Hey Andre,

Do you have any input on the placement of a WBO2 Sensor in relation to a Catalytic Converter. I have seen many people use a Tail Pipe Mount for their O2 Sensors, which is obviously Post-Cat. Wouldn't this affect their AFR reading and give an inaccurate measurement? Thanks for any input!

I know there is a belief that the catalytic convertor will effect the lambda values being measured, however under steady state conditions or for example during a normal ramp run on a dyno, the accuracy of the reading isn't affected. You will find that the post cat readings are a little slower in their response to fast transients though.

Here's a useful resource that looks into the cat's effect on AFR -

Hey Andre,

I had actually come across that link before, the results seemed reasonable. I just was curious as to your experience/methods. Thanks for the input!