[QWKSNKE]

Originally Posted by Sendero

Why do the Wideband installation instructions tell you to put the O2 sensor in upstream of the cats because it will give inaccurate readings if the sensor is placed downstream of the cats when all major dyno's use a Wideband sensor that sticks into the tailpipe?

Because the cats do remove part of the fuel that is coming out (which is part of their job)of the exhaust.

I believe we have already discussed issue between 'tailpipe' widebands and real widebands. The tail pipe ones are not as accurate but at the same time I do believe they sample a little different.